How To Create Junit Test Class In Intellij
1. Overview
The goal of this document is to provide comprehensive reference documentation for programmers writing tests, extension authors, and engine authors as well as build tool and IDE vendors.
This document is also available as a PDF download.
1.1. What is JUnit 5?
Unlike previous versions of JUnit, JUnit 5 is composed of several different modules from three different sub-projects.
JUnit 5 = JUnit Platform + JUnit Jupiter + JUnit Vintage
The JUnit Platform serves as a foundation for launching testing frameworks on the JVM. It also defines the TestEngine API for developing a testing framework that runs on the platform. Furthermore, the platform provides a Console Launcher to launch the platform from the command line and a JUnit 4 based Runner for running any TestEngine on the platform in a JUnit 4 based environment. First-class support for the JUnit Platform also exists in popular IDEs (see IntelliJ IDEA, Eclipse, NetBeans, and Visual Studio Code) and build tools (see Gradle, Maven, and Ant).
JUnit Jupiter is the combination of the new programming model and extension model for writing tests and extensions in JUnit 5. The Jupiter sub-project provides a TestEngine for running Jupiter based tests on the platform.
JUnit Vintage provides a TestEngine for running JUnit 3 and JUnit 4 based tests on the platform. It requires JUnit 4.12 or later to be present on the class/module path.
1.2. Supported Java Versions
JUnit 5 requires Java 8 (or higher) at runtime. However, you can still test code that has been compiled with previous versions of the JDK.
1.3. Getting Help
1.4. Getting Started
1.4.1. Downloading JUnit Artifacts
To find out what artifacts are available for download and inclusion in your project, refer to Dependency Metadata. To set up dependency management for your build, refer to Build Support and the Example Projects.
1.4.2. JUnit 5 Features
To find out what features are available in JUnit 5 and how to use them, read the corresponding sections of this User Guide, organized by topic.
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Writing Tests in JUnit Jupiter
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Migrating from JUnit 4 to JUnit Jupiter
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Running Tests
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Extension Model for JUnit Jupiter
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Advanced Topics
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JUnit Platform Launcher API
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JUnit Platform Test Kit
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1.4.3. Example Projects
To see complete, working examples of projects that you can copy and experiment with, the junit5-samples repository is a good place to start. The junit5-samples repository hosts a collection of sample projects based on JUnit Jupiter, JUnit Vintage, and other testing frameworks. You'll find appropriate build scripts (e.g., build.gradle, pom.xml, etc.) in the example projects. The links below highlight some of the combinations you can choose from.
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For Gradle and Java, check out the
junit5-jupiter-starter-gradleproject. -
For Gradle and Kotlin, check out the
junit5-jupiter-starter-gradle-kotlinproject. -
For Gradle and Groovy, check out the
junit5-jupiter-starter-gradle-groovyproject. -
For Maven, check out the
junit5-jupiter-starter-mavenproject. -
For Ant, check out the
junit5-jupiter-starter-antproject.
2. Writing Tests
The following example provides a glimpse at the minimum requirements for writing a test in JUnit Jupiter. Subsequent sections of this chapter will provide further details on all available features.
A first test case
import static org . junit . jupiter . api . Assertions . assertEquals ; import example.util.Calculator ; import org.junit.jupiter.api.Test ; class MyFirstJUnitJupiterTests { private final Calculator calculator = new Calculator (); @Test void addition () { assertEquals ( 2 , calculator . add ( 1 , 1 )); } } 2.1. Annotations
JUnit Jupiter supports the following annotations for configuring tests and extending the framework.
Unless otherwise stated, all core annotations are located in the org.junit.jupiter.api package in the junit-jupiter-api module.
| Annotation | Description |
|---|---|
| | Denotes that a method is a test method. Unlike JUnit 4's |
| | Denotes that a method is a parameterized test. Such methods are inherited unless they are overridden. |
| | Denotes that a method is a test template for a repeated test. Such methods are inherited unless they are overridden. |
| | Denotes that a method is a test factory for dynamic tests. Such methods are inherited unless they are overridden. |
| | Denotes that a method is a template for test cases designed to be invoked multiple times depending on the number of invocation contexts returned by the registered providers. Such methods are inherited unless they are overridden. |
| | Used to configure the test class execution order for |
| | Used to configure the test method execution order for the annotated test class; similar to JUnit 4's |
| | Used to configure the test instance lifecycle for the annotated test class. Such annotations are inherited. |
| | Declares a custom display name for the test class or test method. Such annotations are not inherited. |
| | Declares a custom display name generator for the test class. Such annotations are inherited. |
| | Denotes that the annotated method should be executed before each |
| | Denotes that the annotated method should be executed after each |
| | Denotes that the annotated method should be executed before all |
| | Denotes that the annotated method should be executed after all |
| | Denotes that the annotated class is a non-static nested test class. |
| | Used to declare tags for filtering tests, either at the class or method level; analogous to test groups in TestNG or Categories in JUnit 4. Such annotations are inherited at the class level but not at the method level. |
| | Used to disable a test class or test method; analogous to JUnit 4's |
| | Used to fail a test, test factory, test template, or lifecycle method if its execution exceeds a given duration. Such annotations are inherited. |
| | Used to register extensions declaratively. Such annotations are inherited. |
| | Used to register extensions programmatically via fields. Such fields are inherited unless they are shadowed. |
| | Used to supply a temporary directory via field injection or parameter injection in a lifecycle method or test method; located in the |
| Some annotations may currently be experimental. Consult the table in Experimental APIs for details. |
2.1.1. Meta-Annotations and Composed Annotations
JUnit Jupiter annotations can be used as meta-annotations. That means that you can define your own composed annotation that will automatically inherit the semantics of its meta-annotations.
For example, instead of copying and pasting @Tag("fast") throughout your code base (see Tagging and Filtering), you can create a custom composed annotation named @Fast as follows. @Fast can then be used as a drop-in replacement for @Tag("fast").
import java.lang.annotation.ElementType ; import java.lang.annotation.Retention ; import java.lang.annotation.RetentionPolicy ; import java.lang.annotation.Target ; import org.junit.jupiter.api.Tag ; @Target ({ ElementType . TYPE , ElementType . METHOD }) @Retention ( RetentionPolicy . RUNTIME ) @Tag ( "fast" ) public @interface Fast { } The following @Test method demonstrates usage of the @Fast annotation.
@Fast @Test void myFastTest () { // ... } You can even take that one step further by introducing a custom @FastTest annotation that can be used as a drop-in replacement for @Tag("fast") and @Test.
import java.lang.annotation.ElementType ; import java.lang.annotation.Retention ; import java.lang.annotation.RetentionPolicy ; import java.lang.annotation.Target ; import org.junit.jupiter.api.Tag ; import org.junit.jupiter.api.Test ; @Target ( ElementType . METHOD ) @Retention ( RetentionPolicy . RUNTIME ) @Tag ( "fast" ) @Test public @interface FastTest { } JUnit automatically recognizes the following as a @Test method that is tagged with "fast".
@FastTest void myFastTest () { // ... } 2.2. Test Classes and Methods
Test Class: any top-level class, static member class, or @Nested class that contains at least one test method.
Test classes must not be abstract and must have a single constructor.
Test Method: any instance method that is directly annotated or meta-annotated with @Test, @RepeatedTest, @ParameterizedTest, @TestFactory, or @TestTemplate.
Lifecycle Method: any method that is directly annotated or meta-annotated with @BeforeAll, @AfterAll, @BeforeEach, or @AfterEach.
Test methods and lifecycle methods may be declared locally within the current test class, inherited from superclasses, or inherited from interfaces (see Test Interfaces and Default Methods). In addition, test methods and lifecycle methods must not be abstract and must not return a value (except @TestFactory methods which are required to return a value).
| Class and method visibility Test classes, test methods, and lifecycle methods are not required to be It is generally recommended to omit the |
The following test class demonstrates the use of @Test methods and all supported lifecycle methods. For further information on runtime semantics, see Test Execution Order and Wrapping Behavior of Callbacks.
A standard test class
import static org . junit . jupiter . api . Assertions . fail ; import static org . junit . jupiter . api . Assumptions . assumeTrue ; import org.junit.jupiter.api.AfterAll ; import org.junit.jupiter.api.AfterEach ; import org.junit.jupiter.api.BeforeAll ; import org.junit.jupiter.api.BeforeEach ; import org.junit.jupiter.api.Disabled ; import org.junit.jupiter.api.Test ; class StandardTests { @BeforeAll static void initAll () { } @BeforeEach void init () { } @Test void succeedingTest () { } @Test void failingTest () { fail ( "a failing test" ); } @Test @Disabled ( "for demonstration purposes" ) void skippedTest () { // not executed } @Test void abortedTest () { assumeTrue ( "abc" . contains ( "Z" )); fail ( "test should have been aborted" ); } @AfterEach void tearDown () { } @AfterAll static void tearDownAll () { } } 2.3. Display Names
Test classes and test methods can declare custom display names via @DisplayName — with spaces, special characters, and even emojis — that will be displayed in test reports and by test runners and IDEs.
import org.junit.jupiter.api.DisplayName ; import org.junit.jupiter.api.Test ; @DisplayName ( "A special test case" ) class DisplayNameDemo { @Test @DisplayName ( "Custom test name containing spaces" ) void testWithDisplayNameContainingSpaces () { } @Test @DisplayName ( "╯°□°）╯" ) void testWithDisplayNameContainingSpecialCharacters () { } @Test @DisplayName ( "😱" ) void testWithDisplayNameContainingEmoji () { } } 2.3.1. Display Name Generators
JUnit Jupiter supports custom display name generators that can be configured via the @DisplayNameGeneration annotation. Values provided via @DisplayName annotations always take precedence over display names generated by a DisplayNameGenerator.
Generators can be created by implementing DisplayNameGenerator. Here are some default ones available in Jupiter:
| DisplayNameGenerator | Behavior |
|---|---|
| | Matches the standard display name generation behavior in place since JUnit Jupiter 5.0 was released. |
| | Removes trailing parentheses for methods with no parameters. |
| | Replaces underscores with spaces. |
| | Generates complete sentences by concatenating the names of the test and the enclosing classes. |
Note that for IndicativeSentences, you can customize the separator and the underlying generator by using @IndicativeSentencesGeneration as shown in the following example.
import org.junit.jupiter.api.DisplayName ; import org.junit.jupiter.api.DisplayNameGeneration ; import org.junit.jupiter.api.DisplayNameGenerator ; import org.junit.jupiter.api.IndicativeSentencesGeneration ; import org.junit.jupiter.api.Nested ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.params.ParameterizedTest ; import org.junit.jupiter.params.provider.ValueSource ; class DisplayNameGeneratorDemo { @Nested @DisplayNameGeneration ( DisplayNameGenerator . ReplaceUnderscores . class ) class A_year_is_not_supported { @Test void if_it_is_zero () { } @DisplayName ( "A negative value for year is not supported by the leap year computation." ) @ParameterizedTest ( name = "For example, year {0} is not supported." ) @ValueSource ( ints = { - 1 , - 4 }) void if_it_is_negative ( int year ) { } } @Nested @IndicativeSentencesGeneration ( separator = " -> " , generator = DisplayNameGenerator . ReplaceUnderscores . class ) class A_year_is_a_leap_year { @Test void if_it_is_divisible_by_4_but_not_by_100 () { } @ParameterizedTest ( name = "Year {0} is a leap year." ) @ValueSource ( ints = { 2016 , 2020 , 2048 }) void if_it_is_one_of_the_following_years ( int year ) { } } } +-- DisplayNameGeneratorDemo [OK] +-- A year is not supported [OK] | +-- A negative value for year is not supported by the leap year computation. [OK] | | +-- For example, year -1 is not supported. [OK] | | '-- For example, year -4 is not supported. [OK] | '-- if it is zero() [OK] '-- A year is a leap year [OK] +-- A year is a leap year -> if it is divisible by 4 but not by 100. [OK] '-- A year is a leap year -> if it is one of the following years. [OK] +-- Year 2016 is a leap year. [OK] +-- Year 2020 is a leap year. [OK] '-- Year 2048 is a leap year. [OK] 2.3.2. Setting the Default Display Name Generator
You can use the junit.jupiter.displayname.generator.default configuration parameter to specify the fully qualified class name of the DisplayNameGenerator you would like to use by default. Just like for display name generators configured via the @DisplayNameGeneration annotation, the supplied class has to implement the DisplayNameGenerator interface. The default display name generator will be used for all tests unless the @DisplayNameGeneration annotation is present on an enclosing test class or test interface. Values provided via @DisplayName annotations always take precedence over display names generated by a DisplayNameGenerator.
For example, to use the ReplaceUnderscores display name generator by default, you should set the configuration parameter to the corresponding fully qualified class name (e.g., in src/test/resources/junit-platform.properties):
junit.jupiter.displayname.generator.default = \ org.junit.jupiter.api.DisplayNameGenerator$ReplaceUnderscores Similarly, you can specify the fully qualified name of any custom class that implements DisplayNameGenerator.
In summary, the display name for a test class or method is determined according to the following precedence rules:
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value of the
@DisplayNameannotation, if present -
by calling the
DisplayNameGeneratorspecified in the@DisplayNameGenerationannotation, if present -
by calling the default
DisplayNameGeneratorconfigured via the configuration parameter, if present -
by calling
org.junit.jupiter.api.DisplayNameGenerator.Standard
2.4. Assertions
JUnit Jupiter comes with many of the assertion methods that JUnit 4 has and adds a few that lend themselves well to being used with Java 8 lambdas. All JUnit Jupiter assertions are static methods in the org.junit.jupiter.api.Assertions class.
import static java . time . Duration . ofMillis ; import static java . time . Duration . ofMinutes ; import static org . junit . jupiter . api . Assertions . assertAll ; import static org . junit . jupiter . api . Assertions . assertEquals ; import static org . junit . jupiter . api . Assertions . assertNotNull ; import static org . junit . jupiter . api . Assertions . assertThrows ; import static org . junit . jupiter . api . Assertions . assertTimeout ; import static org . junit . jupiter . api . Assertions . assertTimeoutPreemptively ; import static org . junit . jupiter . api . Assertions . assertTrue ; import java.util.concurrent.CountDownLatch ; import example.domain.Person ; import example.util.Calculator ; import org.junit.jupiter.api.Test ; class AssertionsDemo { private final Calculator calculator = new Calculator (); private final Person person = new Person ( "Jane" , "Doe" ); @Test void standardAssertions () { assertEquals ( 2 , calculator . add ( 1 , 1 )); assertEquals ( 4 , calculator . multiply ( 2 , 2 ), "The optional failure message is now the last parameter" ); assertTrue ( 'a' < 'b' , () -> "Assertion messages can be lazily evaluated -- " + "to avoid constructing complex messages unnecessarily." ); } @Test void groupedAssertions () { // In a grouped assertion all assertions are executed, and all // failures will be reported together. assertAll ( "person" , () -> assertEquals ( "Jane" , person . getFirstName ()), () -> assertEquals ( "Doe" , person . getLastName ()) ); } @Test void dependentAssertions () { // Within a code block, if an assertion fails the // subsequent code in the same block will be skipped. assertAll ( "properties" , () -> { String firstName = person . getFirstName (); assertNotNull ( firstName ); // Executed only if the previous assertion is valid. assertAll ( "first name" , () -> assertTrue ( firstName . startsWith ( "J" )), () -> assertTrue ( firstName . endsWith ( "e" )) ); }, () -> { // Grouped assertion, so processed independently // of results of first name assertions. String lastName = person . getLastName (); assertNotNull ( lastName ); // Executed only if the previous assertion is valid. assertAll ( "last name" , () -> assertTrue ( lastName . startsWith ( "D" )), () -> assertTrue ( lastName . endsWith ( "e" )) ); } ); } @Test void exceptionTesting () { Exception exception = assertThrows ( ArithmeticException . class , () -> calculator . divide ( 1 , 0 )); assertEquals ( "/ by zero" , exception . getMessage ()); } @Test void timeoutNotExceeded () { // The following assertion succeeds. assertTimeout ( ofMinutes ( 2 ), () -> { // Perform task that takes less than 2 minutes. }); } @Test void timeoutNotExceededWithResult () { // The following assertion succeeds, and returns the supplied object. String actualResult = assertTimeout ( ofMinutes ( 2 ), () -> { return "a result" ; }); assertEquals ( "a result" , actualResult ); } @Test void timeoutNotExceededWithMethod () { // The following assertion invokes a method reference and returns an object. String actualGreeting = assertTimeout ( ofMinutes ( 2 ), AssertionsDemo: : greeting ); assertEquals ( "Hello, World!" , actualGreeting ); } @Test void timeoutExceeded () { // The following assertion fails with an error message similar to: // execution exceeded timeout of 10 ms by 91 ms assertTimeout ( ofMillis ( 10 ), () -> { // Simulate task that takes more than 10 ms. Thread . sleep ( 100 ); }); } @Test void timeoutExceededWithPreemptiveTermination () { // The following assertion fails with an error message similar to: // execution timed out after 10 ms assertTimeoutPreemptively ( ofMillis ( 10 ), () -> { // Simulate task that takes more than 10 ms. new CountDownLatch ( 1 ). await (); }); } private static String greeting () { return "Hello, World!" ; } } | Preemptive Timeouts with Contrary to declarative timeouts, the various One common example of this is the transactional testing support in the Spring Framework. Specifically, Spring's testing support binds transaction state to the current thread (via a Similar side effects may be encountered with other frameworks that rely on |
2.4.1. Kotlin Assertion Support
JUnit Jupiter also comes with a few assertion methods that lend themselves well to being used in Kotlin. All JUnit Jupiter Kotlin assertions are top-level functions in the org.junit.jupiter.api package.
import example.domain.Person import example.util.Calculator import java.time.Duration import org.junit.jupiter.api.Assertions.assertEquals import org.junit.jupiter.api.Assertions.assertTrue import org.junit.jupiter.api.Test import org.junit.jupiter.api.assertAll import org.junit.jupiter.api.assertDoesNotThrow import org.junit.jupiter.api.assertThrows import org.junit.jupiter.api.assertTimeout import org.junit.jupiter.api.assertTimeoutPreemptively class KotlinAssertionsDemo { private val person = Person ( "Jane" , "Doe" ) private val people = setOf ( person , Person ( "John" , "Doe" )) @Test fun `exception absence testing` () { val calculator = Calculator () val result = assertDoesNotThrow ( "Should not throw an exception" ) { calculator . divide ( 0 , 1 ) } assertEquals ( 0 , result ) } @Test fun `expected exception testing` () { val calculator = Calculator () val exception = assertThrows < ArithmeticException > ( "Should throw an exception" ) { calculator . divide ( 1 , 0 ) } assertEquals ( "/ by zero" , exception . message ) } @Test fun `grouped assertions` () { assertAll ( "Person properties" , { assertEquals ( "Jane" , person . firstName ) }, { assertEquals ( "Doe" , person . lastName ) } ) } @Test fun `grouped assertions from a stream` () { assertAll ( "People with first name starting with J" , people . stream () . map { // This mapping returns Stream<() -> Unit> { assertTrue ( it . firstName . startsWith ( "J" )) } } ) } @Test fun `grouped assertions from a collection` () { assertAll ( "People with last name of Doe" , people . map { { assertEquals ( "Doe" , it . lastName ) } } ) } @Test fun `timeout not exceeded testing` () { val fibonacciCalculator = FibonacciCalculator () val result = assertTimeout ( Duration . ofMillis ( 1000 )) { fibonacciCalculator . fib ( 14 ) } assertEquals ( 377 , result ) } @Test fun `timeout exceeded with preemptive termination` () { // The following assertion fails with an error message similar to: // execution timed out after 10 ms assertTimeoutPreemptively ( Duration . ofMillis ( 10 )) { // Simulate task that takes more than 10 ms. Thread . sleep ( 100 ) } } } 2.4.2. Third-party Assertion Libraries
Even though the assertion facilities provided by JUnit Jupiter are sufficient for many testing scenarios, there are times when more power and additional functionality such as matchers are desired or required. In such cases, the JUnit team recommends the use of third-party assertion libraries such as AssertJ, Hamcrest, Truth, etc. Developers are therefore free to use the assertion library of their choice.
For example, the combination of matchers and a fluent API can be used to make assertions more descriptive and readable. However, JUnit Jupiter's org.junit.jupiter.api.Assertions class does not provide an assertThat() method like the one found in JUnit 4's org.junit.Assert class which accepts a Hamcrest Matcher. Instead, developers are encouraged to use the built-in support for matchers provided by third-party assertion libraries.
The following example demonstrates how to use the assertThat() support from Hamcrest in a JUnit Jupiter test. As long as the Hamcrest library has been added to the classpath, you can statically import methods such as assertThat(), is(), and equalTo() and then use them in tests like in the assertWithHamcrestMatcher() method below.
import static org . hamcrest . CoreMatchers . equalTo ; import static org . hamcrest . CoreMatchers . is ; import static org . hamcrest . MatcherAssert . assertThat ; import example.util.Calculator ; import org.junit.jupiter.api.Test ; class HamcrestAssertionsDemo { private final Calculator calculator = new Calculator (); @Test void assertWithHamcrestMatcher () { assertThat ( calculator . subtract ( 4 , 1 ), is ( equalTo ( 3 ))); } } Naturally, legacy tests based on the JUnit 4 programming model can continue using org.junit.Assert#assertThat.
2.5. Assumptions
JUnit Jupiter comes with a subset of the assumption methods that JUnit 4 provides and adds a few that lend themselves well to being used with Java 8 lambda expressions and method references. All JUnit Jupiter assumptions are static methods in the org.junit.jupiter.api.Assumptions class.
import static org . junit . jupiter . api . Assertions . assertEquals ; import static org . junit . jupiter . api . Assumptions . assumeTrue ; import static org . junit . jupiter . api . Assumptions . assumingThat ; import example.util.Calculator ; import org.junit.jupiter.api.Test ; class AssumptionsDemo { private final Calculator calculator = new Calculator (); @Test void testOnlyOnCiServer () { assumeTrue ( "CI" . equals ( System . getenv ( "ENV" ))); // remainder of test } @Test void testOnlyOnDeveloperWorkstation () { assumeTrue ( "DEV" . equals ( System . getenv ( "ENV" )), () -> "Aborting test: not on developer workstation" ); // remainder of test } @Test void testInAllEnvironments () { assumingThat ( "CI" . equals ( System . getenv ( "ENV" )), () -> { // perform these assertions only on the CI server assertEquals ( 2 , calculator . divide ( 4 , 2 )); }); // perform these assertions in all environments assertEquals ( 42 , calculator . multiply ( 6 , 7 )); } } As of JUnit Jupiter 5.4, it is also possible to use methods from JUnit 4's org.junit.Assume class for assumptions. Specifically, JUnit Jupiter supports JUnit 4's AssumptionViolatedException to signal that a test should be aborted instead of marked as a failure. |
2.6. Disabling Tests
Entire test classes or individual test methods may be disabled via the @Disabled annotation, via one of the annotations discussed in Conditional Test Execution, or via a custom ExecutionCondition.
Here's a @Disabled test class.
import org.junit.jupiter.api.Disabled ; import org.junit.jupiter.api.Test ; @Disabled ( "Disabled until bug #99 has been fixed" ) class DisabledClassDemo { @Test void testWillBeSkipped () { } } And here's a test class that contains a @Disabled test method.
import org.junit.jupiter.api.Disabled ; import org.junit.jupiter.api.Test ; class DisabledTestsDemo { @Disabled ( "Disabled until bug #42 has been resolved" ) @Test void testWillBeSkipped () { } @Test void testWillBeExecuted () { } } @Disabled may be declared without providing a reason; however, the JUnit team recommends that developers provide a short explanation for why a test class or test method has been disabled. Consequently, the above examples both show the use of a reason — for example, @Disabled("Disabled until bug #42 has been resolved"). Some development teams even require the presence of issue tracking numbers in the reason for automated traceability, etc. |
2.7. Conditional Test Execution
The ExecutionCondition extension API in JUnit Jupiter allows developers to either enable or disable a container or test based on certain conditions programmatically. The simplest example of such a condition is the built-in DisabledCondition which supports the @Disabled annotation (see Disabling Tests). In addition to @Disabled, JUnit Jupiter also supports several other annotation-based conditions in the org.junit.jupiter.api.condition package that allow developers to enable or disable containers and tests declaratively. When multiple ExecutionCondition extensions are registered, a container or test is disabled as soon as one of the conditions returns disabled. If you wish to provide details about why they might be disabled, every annotation associated with these built-in conditions has a disabledReason attribute available for that purpose.
See ExecutionCondition and the following sections for details.
| Composed Annotations Note that any of the conditional annotations listed in the following sections may also be used as a meta-annotation in order to create a custom composed annotation. For example, the |
| Unless otherwise stated, each of the conditional annotations listed in the following sections can only be declared once on a given test interface, test class, or test method. If a conditional annotation is directly present, indirectly present, or meta-present multiple times on a given element, only the first such annotation discovered by JUnit will be used; any additional declarations will be silently ignored. Note, however, that each conditional annotation may be used in conjunction with other conditional annotations in the |
2.7.1. Operating System Conditions
A container or test may be enabled or disabled on a particular operating system via the @EnabledOnOs and @DisabledOnOs annotations.
@Test @EnabledOnOs ( MAC ) void onlyOnMacOs () { // ... } @TestOnMac void testOnMac () { // ... } @Test @EnabledOnOs ({ LINUX , MAC }) void onLinuxOrMac () { // ... } @Test @DisabledOnOs ( WINDOWS ) void notOnWindows () { // ... } @Target ( ElementType . METHOD ) @Retention ( RetentionPolicy . RUNTIME ) @Test @EnabledOnOs ( MAC ) @interface TestOnMac { } 2.7.2. Java Runtime Environment Conditions
A container or test may be enabled or disabled on particular versions of the Java Runtime Environment (JRE) via the @EnabledOnJre and @DisabledOnJre annotations or on a particular range of versions of the JRE via the @EnabledForJreRange and @DisabledForJreRange annotations. The range defaults to JRE.JAVA_8 as the lower border (min) and JRE.OTHER as the higher border (max), which allows usage of half open ranges.
@Test @EnabledOnJre ( JAVA_8 ) void onlyOnJava8 () { // ... } @Test @EnabledOnJre ({ JAVA_9 , JAVA_10 }) void onJava9Or10 () { // ... } @Test @EnabledForJreRange ( min = JAVA_9 , max = JAVA_11 ) void fromJava9to11 () { // ... } @Test @EnabledForJreRange ( min = JAVA_9 ) void fromJava9toCurrentJavaFeatureNumber () { // ... } @Test @EnabledForJreRange ( max = JAVA_11 ) void fromJava8To11 () { // ... } @Test @DisabledOnJre ( JAVA_9 ) void notOnJava9 () { // ... } @Test @DisabledForJreRange ( min = JAVA_9 , max = JAVA_11 ) void notFromJava9to11 () { // ... } @Test @DisabledForJreRange ( min = JAVA_9 ) void notFromJava9toCurrentJavaFeatureNumber () { // ... } @Test @DisabledForJreRange ( max = JAVA_11 ) void notFromJava8to11 () { // ... } 2.7.3. System Property Conditions
A container or test may be enabled or disabled based on the value of the named JVM system property via the @EnabledIfSystemProperty and @DisabledIfSystemProperty annotations. The value supplied via the matches attribute will be interpreted as a regular expression.
@Test @EnabledIfSystemProperty ( named = "os.arch" , matches = ".*64.*" ) void onlyOn64BitArchitectures () { // ... } @Test @DisabledIfSystemProperty ( named = "ci-server" , matches = "true" ) void notOnCiServer () { // ... } | As of JUnit Jupiter 5.6, |
2.7.4. Environment Variable Conditions
A container or test may be enabled or disabled based on the value of the named environment variable from the underlying operating system via the @EnabledIfEnvironmentVariable and @DisabledIfEnvironmentVariable annotations. The value supplied via the matches attribute will be interpreted as a regular expression.
@Test @EnabledIfEnvironmentVariable ( named = "ENV" , matches = "staging-server" ) void onlyOnStagingServer () { // ... } @Test @DisabledIfEnvironmentVariable ( named = "ENV" , matches = ".*development.*" ) void notOnDeveloperWorkstation () { // ... } | As of JUnit Jupiter 5.6, |
2.7.5. Custom Conditions
A container or test may be enabled or disabled based on the boolean return of a method via the @EnabledIf and @DisabledIf annotations. The method is provided to the annotation via its name. If needed, the condition method can take a single parameter of type ExtensionContext.
@Test @EnabledIf ( "customCondition" ) void enabled () { // ... } @Test @DisabledIf ( "customCondition" ) void disabled () { // ... } boolean customCondition () { return true ; } Alternatively, the condition method can be located outside the test class. In this case, it has to be referenced by its fully qualified name as demonstrated in the following example.
package example ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.condition.EnabledIf ; class ExternalCustomConditionDemo { @Test @EnabledIf ( "example.ExternalCondition#customCondition" ) void enabled () { // ... } } class ExternalCondition { static boolean customCondition () { return true ; } } When @EnabledIf or @DisabledIf is used at class level, the condition method must always be static. Condition methods located in external classes must also be static. In any other case, you can use both static or instance methods. |
2.8. Tagging and Filtering
Test classes and methods can be tagged via the @Tag annotation. Those tags can later be used to filter test discovery and execution. Please refer to the Tags section for more information about tag support in the JUnit Platform.
import org.junit.jupiter.api.Tag ; import org.junit.jupiter.api.Test ; @Tag ( "fast" ) @Tag ( "model" ) class TaggingDemo { @Test @Tag ( "taxes" ) void testingTaxCalculation () { } } | See Meta-Annotations and Composed Annotations for examples demonstrating how to create custom annotations for tags. |
2.9. Test Execution Order
By default, test classes and methods will be ordered using an algorithm that is deterministic but intentionally nonobvious. This ensures that subsequent runs of a test suite execute test classes and test methods in the same order, thereby allowing for repeatable builds.
| See Test Classes and Methods for a definition of test method and test class. |
2.9.1. Method Order
Although true unit tests typically should not rely on the order in which they are executed, there are times when it is necessary to enforce a specific test method execution order — for example, when writing integration tests or functional tests where the sequence of the tests is important, especially in conjunction with @TestInstance(Lifecycle.PER_CLASS).
To control the order in which test methods are executed, annotate your test class or test interface with @TestMethodOrder and specify the desired MethodOrderer implementation. You can implement your own custom MethodOrderer or use one of the following built-in MethodOrderer implementations.
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MethodOrderer.DisplayName: sorts test methods alphanumerically based on their display names (see display name generation precedence rules) -
MethodOrderer.MethodName: sorts test methods alphanumerically based on their names and formal parameter lists -
MethodOrderer.OrderAnnotation: sorts test methods numerically based on values specified via the@Orderannotation -
MethodOrderer.Random: orders test methods pseudo-randomly and supports configuration of a custom seed -
MethodOrderer.Alphanumeric: sorts test methods alphanumerically based on their names and formal parameter lists; deprecated in favor ofMethodOrderer.MethodName, to be removed in 6.0
The following example demonstrates how to guarantee that test methods are executed in the order specified via the @Order annotation.
import org.junit.jupiter.api.MethodOrderer.OrderAnnotation ; import org.junit.jupiter.api.Order ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.TestMethodOrder ; @TestMethodOrder ( OrderAnnotation . class ) class OrderedTestsDemo { @Test @Order ( 1 ) void nullValues () { // perform assertions against null values } @Test @Order ( 2 ) void emptyValues () { // perform assertions against empty values } @Test @Order ( 3 ) void validValues () { // perform assertions against valid values } } Setting the Default Method Orderer
You can use the junit.jupiter.testmethod.order.default configuration parameter to specify the fully qualified class name of the MethodOrderer you would like to use by default. Just like for the orderer configured via the @TestMethodOrder annotation, the supplied class has to implement the MethodOrderer interface. The default orderer will be used for all tests unless the @TestMethodOrder annotation is present on an enclosing test class or test interface.
For example, to use the MethodOrderer.OrderAnnotation method orderer by default, you should set the configuration parameter to the corresponding fully qualified class name (e.g., in src/test/resources/junit-platform.properties):
junit.jupiter.testmethod.order.default = \ org.junit.jupiter.api.MethodOrderer$OrderAnnotation Similarly, you can specify the fully qualified name of any custom class that implements MethodOrderer.
2.9.2. Class Order
Although test classes typically should not rely on the order in which they are executed, there are times when it is desirable to enforce a specific test class execution order. You may wish to execute test classes in a random order to ensure there are no accidental dependencies between test classes, or you may wish to order test classes to optimize build time as outlined in the following scenarios.
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Run previously failing tests and faster tests first: "fail fast" mode
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With parallel execution enabled, run longer tests first: "shortest test plan execution duration" mode
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Various other use cases
To configure test class execution order globally for the entire test suite, use the junit.jupiter.testclass.order.default configuration parameter to specify the fully qualified class name of the ClassOrderer you would like to use. The supplied class must implement the ClassOrderer interface.
You can implement your own custom ClassOrderer or use one of the following built-in ClassOrderer implementations.
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ClassOrderer.ClassName: sorts test classes alphanumerically based on their fully qualified class names -
ClassOrderer.DisplayName: sorts test classes alphanumerically based on their display names (see display name generation precedence rules) -
ClassOrderer.OrderAnnotation: sorts test classes numerically based on values specified via the@Orderannotation -
ClassOrderer.Random: orders test classes pseudo-randomly and supports configuration of a custom seed
For example, for the @Order annotation to be honored on test classes, you should configure the ClassOrderer.OrderAnnotation class orderer using the configuration parameter with the corresponding fully qualified class name (e.g., in src/test/resources/junit-platform.properties):
junit.jupiter.testclass.order.default = \ org.junit.jupiter.api.ClassOrderer$OrderAnnotation The configured ClassOrderer will be applied to all top-level test classes (including static nested test classes) and @Nested test classes.
Top-level test classes will be ordered relative to each other; whereas, @Nested test classes will be ordered relative to other @Nested test classes sharing the same enclosing class. |
To configure test class execution order locally for @Nested test classes, declare the @TestClassOrder annotation on the enclosing class for the @Nested test classes you want to order, and supply a class reference to the ClassOrderer implementation you would like to use directly in the @TestClassOrder annotation. The configured ClassOrderer will be applied recursively to @Nested test classes and their @Nested test classes. Note that a local @TestClassOrder declaration always overrides an inherited @TestClassOrder declaration or a ClassOrderer configured globally via the junit.jupiter.testclass.order.default configuration parameter.
The following example demonstrates how to guarantee that @Nested test classes are executed in the order specified via the @Order annotation.
import org.junit.jupiter.api.ClassOrderer ; import org.junit.jupiter.api.Nested ; import org.junit.jupiter.api.Order ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.TestClassOrder ; @TestClassOrder ( ClassOrderer . OrderAnnotation . class ) class OrderedNestedTestClassesDemo { @Nested @Order ( 1 ) class PrimaryTests { @Test void test1 () { } } @Nested @Order ( 2 ) class SecondaryTests { @Test void test2 () { } } } 2.10. Test Instance Lifecycle
In order to allow individual test methods to be executed in isolation and to avoid unexpected side effects due to mutable test instance state, JUnit creates a new instance of each test class before executing each test method (see Test Classes and Methods). This "per-method" test instance lifecycle is the default behavior in JUnit Jupiter and is analogous to all previous versions of JUnit.
Please note that the test class will still be instantiated if a given test method is disabled via a condition (e.g., @Disabled, @DisabledOnOs, etc.) even when the "per-method" test instance lifecycle mode is active. |
If you would prefer that JUnit Jupiter execute all test methods on the same test instance, annotate your test class with @TestInstance(Lifecycle.PER_CLASS). When using this mode, a new test instance will be created once per test class. Thus, if your test methods rely on state stored in instance variables, you may need to reset that state in @BeforeEach or @AfterEach methods.
The "per-class" mode has some additional benefits over the default "per-method" mode. Specifically, with the "per-class" mode it becomes possible to declare @BeforeAll and @AfterAll on non-static methods as well as on interface default methods. The "per-class" mode therefore also makes it possible to use @BeforeAll and @AfterAll methods in @Nested test classes.
If you are authoring tests using the Kotlin programming language, you may also find it easier to implement @BeforeAll and @AfterAll methods by switching to the "per-class" test instance lifecycle mode.
2.10.1. Changing the Default Test Instance Lifecycle
If a test class or test interface is not annotated with @TestInstance, JUnit Jupiter will use a default lifecycle mode. The standard default mode is PER_METHOD; however, it is possible to change the default for the execution of an entire test plan. To change the default test instance lifecycle mode, set the junit.jupiter.testinstance.lifecycle.default configuration parameter to the name of an enum constant defined in TestInstance.Lifecycle, ignoring case. This can be supplied as a JVM system property, as a configuration parameter in the LauncherDiscoveryRequest that is passed to the Launcher, or via the JUnit Platform configuration file (see Configuration Parameters for details).
For example, to set the default test instance lifecycle mode to Lifecycle.PER_CLASS, you can start your JVM with the following system property.
-Djunit.jupiter.testinstance.lifecycle.default=per_class
Note, however, that setting the default test instance lifecycle mode via the JUnit Platform configuration file is a more robust solution since the configuration file can be checked into a version control system along with your project and can therefore be used within IDEs and your build software.
To set the default test instance lifecycle mode to Lifecycle.PER_CLASS via the JUnit Platform configuration file, create a file named junit-platform.properties in the root of the class path (e.g., src/test/resources) with the following content.
junit.jupiter.testinstance.lifecycle.default = per_class
| Changing the default test instance lifecycle mode can lead to unpredictable results and fragile builds if not applied consistently. For example, if the build configures "per-class" semantics as the default but tests in the IDE are executed using "per-method" semantics, that can make it difficult to debug errors that occur on the build server. It is therefore recommended to change the default in the JUnit Platform configuration file instead of via a JVM system property. |
2.11. Nested Tests
@Nested tests give the test writer more capabilities to express the relationship among several groups of tests. Such nested tests make use of Java's nested classes and facilitate hierarchical thinking about the test structure. Here's an elaborate example, both as source code and as a screenshot of the execution within an IDE.
Nested test suite for testing a stack
import static org . junit . jupiter . api . Assertions . assertEquals ; import static org . junit . jupiter . api . Assertions . assertFalse ; import static org . junit . jupiter . api . Assertions . assertThrows ; import static org . junit . jupiter . api . Assertions . assertTrue ; import java.util.EmptyStackException ; import java.util.Stack ; import org.junit.jupiter.api.BeforeEach ; import org.junit.jupiter.api.DisplayName ; import org.junit.jupiter.api.Nested ; import org.junit.jupiter.api.Test ; @DisplayName ( "A stack" ) class TestingAStackDemo { Stack < Object > stack ; @Test @DisplayName ( "is instantiated with new Stack()" ) void isInstantiatedWithNew () { new Stack <>(); } @Nested @DisplayName ( "when new" ) class WhenNew { @BeforeEach void createNewStack () { stack = new Stack <>(); } @Test @DisplayName ( "is empty" ) void isEmpty () { assertTrue ( stack . isEmpty ()); } @Test @DisplayName ( "throws EmptyStackException when popped" ) void throwsExceptionWhenPopped () { assertThrows ( EmptyStackException . class , stack: : pop ); } @Test @DisplayName ( "throws EmptyStackException when peeked" ) void throwsExceptionWhenPeeked () { assertThrows ( EmptyStackException . class , stack: : peek ); } @Nested @DisplayName ( "after pushing an element" ) class AfterPushing { String anElement = "an element" ; @BeforeEach void pushAnElement () { stack . push ( anElement ); } @Test @DisplayName ( "it is no longer empty" ) void isNotEmpty () { assertFalse ( stack . isEmpty ()); } @Test @DisplayName ( "returns the element when popped and is empty" ) void returnElementWhenPopped () { assertEquals ( anElement , stack . pop ()); assertTrue ( stack . isEmpty ()); } @Test @DisplayName ( "returns the element when peeked but remains not empty" ) void returnElementWhenPeeked () { assertEquals ( anElement , stack . peek ()); assertFalse ( stack . isEmpty ()); } } } } When executing this example in an IDE, the test execution tree in the GUI will look similar to the following image.
Executing a nested test in an IDE
In this example, preconditions from outer tests are used in inner tests by defining hierarchical lifecycle methods for the setup code. For example, createNewStack() is a @BeforeEach lifecycle method that is used in the test class in which it is defined and in all levels in the nesting tree below the class in which it is defined.
The fact that setup code from outer tests is run before inner tests are executed gives you the ability to run all tests independently. You can even run inner tests alone without running the outer tests, because the setup code from the outer tests is always executed.
Only non-static nested classes (i.e. inner classes) can serve as @Nested test classes. Nesting can be arbitrarily deep, and those inner classes are subject to full lifecycle support with one exception: @BeforeAll and @AfterAll methods do not work by default. The reason is that Java does not allow static members in inner classes. However, this restriction can be circumvented by annotating a @Nested test class with @TestInstance(Lifecycle.PER_CLASS) (see Test Instance Lifecycle). |
2.12. Dependency Injection for Constructors and Methods
In all prior JUnit versions, test constructors or methods were not allowed to have parameters (at least not with the standard Runner implementations). As one of the major changes in JUnit Jupiter, both test constructors and methods are now permitted to have parameters. This allows for greater flexibility and enables Dependency Injection for constructors and methods.
ParameterResolver defines the API for test extensions that wish to dynamically resolve parameters at runtime. If a test class constructor, a test method, or a lifecycle method (see Test Classes and Methods) accepts a parameter, the parameter must be resolved at runtime by a registered ParameterResolver.
There are currently three built-in resolvers that are registered automatically.
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TestInfoParameterResolver: if a constructor or method parameter is of typeTestInfo, theTestInfoParameterResolverwill supply an instance ofTestInfocorresponding to the current container or test as the value for the parameter. TheTestInfocan then be used to retrieve information about the current container or test such as the display name, the test class, the test method, and associated tags. The display name is either a technical name, such as the name of the test class or test method, or a custom name configured via@DisplayName.TestInfoacts as a drop-in replacement for theTestNamerule from JUnit 4. The following demonstrates how to haveTestInfoinjected into a test constructor,@BeforeEachmethod, and@Testmethod.
import static org . junit . jupiter . api . Assertions . assertEquals ; import static org . junit . jupiter . api . Assertions . assertTrue ; import org.junit.jupiter.api.BeforeEach ; import org.junit.jupiter.api.DisplayName ; import org.junit.jupiter.api.Tag ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.TestInfo ; @DisplayName ( "TestInfo Demo" ) class TestInfoDemo { TestInfoDemo ( TestInfo testInfo ) { assertEquals ( "TestInfo Demo" , testInfo . getDisplayName ()); } @BeforeEach void init ( TestInfo testInfo ) { String displayName = testInfo . getDisplayName (); assertTrue ( displayName . equals ( "TEST 1" ) || displayName . equals ( "test2()" )); } @Test @DisplayName ( "TEST 1" ) @Tag ( "my-tag" ) void test1 ( TestInfo testInfo ) { assertEquals ( "TEST 1" , testInfo . getDisplayName ()); assertTrue ( testInfo . getTags (). contains ( "my-tag" )); } @Test void test2 () { } } -
RepetitionInfoParameterResolver: if a method parameter in a@RepeatedTest,@BeforeEach, or@AfterEachmethod is of typeRepetitionInfo, theRepetitionInfoParameterResolverwill supply an instance ofRepetitionInfo.RepetitionInfocan then be used to retrieve information about the current repetition and the total number of repetitions for the corresponding@RepeatedTest. Note, however, thatRepetitionInfoParameterResolveris not registered outside the context of a@RepeatedTest. See Repeated Test Examples. -
TestReporterParameterResolver: if a constructor or method parameter is of typeTestReporter, theTestReporterParameterResolverwill supply an instance ofTestReporter. TheTestReportercan be used to publish additional data about the current test run. The data can be consumed via thereportingEntryPublished()method in aTestExecutionListener, allowing it to be viewed in IDEs or included in reports.In JUnit Jupiter you should use
TestReporterwhere you used to print information tostdoutorstderrin JUnit 4. Using@RunWith(JUnitPlatform.class)will output all reported entries tostdout. In addition, some IDEs print report entries tostdoutor display them in the user interface for test results.
class TestReporterDemo { @Test void reportSingleValue ( TestReporter testReporter ) { testReporter . publishEntry ( "a status message" ); } @Test void reportKeyValuePair ( TestReporter testReporter ) { testReporter . publishEntry ( "a key" , "a value" ); } @Test void reportMultipleKeyValuePairs ( TestReporter testReporter ) { Map < String , String > values = new HashMap <>(); values . put ( "user name" , "dk38" ); values . put ( "award year" , "1974" ); testReporter . publishEntry ( values ); } } Other parameter resolvers must be explicitly enabled by registering appropriate extensions via @ExtendWith. |
Check out the RandomParametersExtension for an example of a custom ParameterResolver. While not intended to be production-ready, it demonstrates the simplicity and expressiveness of both the extension model and the parameter resolution process. MyRandomParametersTest demonstrates how to inject random values into @Test methods.
@ExtendWith ( RandomParametersExtension . class ) class MyRandomParametersTest { @Test void injectsInteger ( @Random int i , @Random int j ) { assertNotEquals ( i , j ); } @Test void injectsDouble ( @Random double d ) { assertEquals ( 0.0 , d , 1.0 ); } } When the type of the parameter to inject is the only condition for your ParameterResolver, you can use the generic TypeBasedParameterResolver base class. The supportsParameters method is implemented behind the scenes and supports parameterized types.
2.13. Test Interfaces and Default Methods
JUnit Jupiter allows @Test, @RepeatedTest, @ParameterizedTest, @TestFactory, @TestTemplate, @BeforeEach, and @AfterEach to be declared on interface default methods. @BeforeAll and @AfterAll can either be declared on static methods in a test interface or on interface default methods if the test interface or test class is annotated with @TestInstance(Lifecycle.PER_CLASS) (see Test Instance Lifecycle). Here are some examples.
@TestInstance ( Lifecycle . PER_CLASS ) interface TestLifecycleLogger { static final Logger logger = Logger . getLogger ( TestLifecycleLogger . class . getName ()); @BeforeAll default void beforeAllTests () { logger . info ( "Before all tests" ); } @AfterAll default void afterAllTests () { logger . info ( "After all tests" ); } @BeforeEach default void beforeEachTest ( TestInfo testInfo ) { logger . info (() -> String . format ( "About to execute [%s]" , testInfo . getDisplayName ())); } @AfterEach default void afterEachTest ( TestInfo testInfo ) { logger . info (() -> String . format ( "Finished executing [%s]" , testInfo . getDisplayName ())); } } interface TestInterfaceDynamicTestsDemo { @TestFactory default Stream < DynamicTest > dynamicTestsForPalindromes () { return Stream . of ( "racecar" , "radar" , "mom" , "dad" ) . map ( text -> dynamicTest ( text , () -> assertTrue ( isPalindrome ( text )))); } } @ExtendWith and @Tag can be declared on a test interface so that classes that implement the interface automatically inherit its tags and extensions. See Before and After Test Execution Callbacks for the source code of the TimingExtension.
@Tag ( "timed" ) @ExtendWith ( TimingExtension . class ) interface TimeExecutionLogger { } In your test class you can then implement these test interfaces to have them applied.
class TestInterfaceDemo implements TestLifecycleLogger , TimeExecutionLogger , TestInterfaceDynamicTestsDemo { @Test void isEqualValue () { assertEquals ( 1 , "a" . length (), "is always equal" ); } } Running the TestInterfaceDemo results in output similar to the following:
INFO example.TestLifecycleLogger - Before all tests INFO example.TestLifecycleLogger - About to execute [dynamicTestsForPalindromes()] INFO example.TimingExtension - Method [dynamicTestsForPalindromes] took 19 ms. INFO example.TestLifecycleLogger - Finished executing [dynamicTestsForPalindromes()] INFO example.TestLifecycleLogger - About to execute [isEqualValue()] INFO example.TimingExtension - Method [isEqualValue] took 1 ms. INFO example.TestLifecycleLogger - Finished executing [isEqualValue()] INFO example.TestLifecycleLogger - After all tests
Another possible application of this feature is to write tests for interface contracts. For example, you can write tests for how implementations of Object.equals or Comparable.compareTo should behave as follows.
public interface Testable < T > { T createValue (); } public interface EqualsContract < T > extends Testable < T > { T createNotEqualValue (); @Test default void valueEqualsItself () { T value = createValue (); assertEquals ( value , value ); } @Test default void valueDoesNotEqualNull () { T value = createValue (); assertFalse ( value . equals ( null )); } @Test default void valueDoesNotEqualDifferentValue () { T value = createValue (); T differentValue = createNotEqualValue (); assertNotEquals ( value , differentValue ); assertNotEquals ( differentValue , value ); } } public interface ComparableContract < T extends Comparable < T >> extends Testable < T > { T createSmallerValue (); @Test default void returnsZeroWhenComparedToItself () { T value = createValue (); assertEquals ( 0 , value . compareTo ( value )); } @Test default void returnsPositiveNumberWhenComparedToSmallerValue () { T value = createValue (); T smallerValue = createSmallerValue (); assertTrue ( value . compareTo ( smallerValue ) > 0 ); } @Test default void returnsNegativeNumberWhenComparedToLargerValue () { T value = createValue (); T smallerValue = createSmallerValue (); assertTrue ( smallerValue . compareTo ( value ) < 0 ); } } In your test class you can then implement both contract interfaces thereby inheriting the corresponding tests. Of course you'll have to implement the abstract methods.
class StringTests implements ComparableContract < String >, EqualsContract < String > { @Override public String createValue () { return "banana" ; } @Override public String createSmallerValue () { return "apple" ; // 'a' < 'b' in "banana" } @Override public String createNotEqualValue () { return "cherry" ; } } | The above tests are merely meant as examples and therefore not complete. |
2.14. Repeated Tests
JUnit Jupiter provides the ability to repeat a test a specified number of times by annotating a method with @RepeatedTest and specifying the total number of repetitions desired. Each invocation of a repeated test behaves like the execution of a regular @Test method with full support for the same lifecycle callbacks and extensions.
The following example demonstrates how to declare a test named repeatedTest() that will be automatically repeated 10 times.
@RepeatedTest ( 10 ) void repeatedTest () { // ... } In addition to specifying the number of repetitions, a custom display name can be configured for each repetition via the name attribute of the @RepeatedTest annotation. Furthermore, the display name can be a pattern composed of a combination of static text and dynamic placeholders. The following placeholders are currently supported.
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{displayName}: display name of the@RepeatedTestmethod -
{currentRepetition}: the current repetition count -
{totalRepetitions}: the total number of repetitions
The default display name for a given repetition is generated based on the following pattern: "repetition {currentRepetition} of {totalRepetitions}". Thus, the display names for individual repetitions of the previous repeatedTest() example would be: repetition 1 of 10, repetition 2 of 10, etc. If you would like the display name of the @RepeatedTest method included in the name of each repetition, you can define your own custom pattern or use the predefined RepeatedTest.LONG_DISPLAY_NAME pattern. The latter is equal to "{displayName} :: repetition {currentRepetition} of {totalRepetitions}" which results in display names for individual repetitions like repeatedTest() :: repetition 1 of 10, repeatedTest() :: repetition 2 of 10, etc.
In order to retrieve information about the current repetition and the total number of repetitions programmatically, a developer can choose to have an instance of RepetitionInfo injected into a @RepeatedTest, @BeforeEach, or @AfterEach method.
2.14.1. Repeated Test Examples
The RepeatedTestsDemo class at the end of this section demonstrates several examples of repeated tests.
The repeatedTest() method is identical to example from the previous section; whereas, repeatedTestWithRepetitionInfo() demonstrates how to have an instance of RepetitionInfo injected into a test to access the total number of repetitions for the current repeated test.
The next two methods demonstrate how to include a custom @DisplayName for the @RepeatedTest method in the display name of each repetition. customDisplayName() combines a custom display name with a custom pattern and then uses TestInfo to verify the format of the generated display name. Repeat! is the {displayName} which comes from the @DisplayName declaration, and 1/1 comes from {currentRepetition}/{totalRepetitions}. In contrast, customDisplayNameWithLongPattern() uses the aforementioned predefined RepeatedTest.LONG_DISPLAY_NAME pattern.
repeatedTestInGerman() demonstrates the ability to translate display names of repeated tests into foreign languages — in this case German, resulting in names for individual repetitions such as: Wiederholung 1 von 5, Wiederholung 2 von 5, etc.
Since the beforeEach() method is annotated with @BeforeEach it will get executed before each repetition of each repeated test. By having the TestInfo and RepetitionInfo injected into the method, we see that it's possible to obtain information about the currently executing repeated test. Executing RepeatedTestsDemo with the INFO log level enabled results in the following output.
INFO: About to execute repetition 1 of 10 for repeatedTest INFO: About to execute repetition 2 of 10 for repeatedTest INFO: About to execute repetition 3 of 10 for repeatedTest INFO: About to execute repetition 4 of 10 for repeatedTest INFO: About to execute repetition 5 of 10 for repeatedTest INFO: About to execute repetition 6 of 10 for repeatedTest INFO: About to execute repetition 7 of 10 for repeatedTest INFO: About to execute repetition 8 of 10 for repeatedTest INFO: About to execute repetition 9 of 10 for repeatedTest INFO: About to execute repetition 10 of 10 for repeatedTest INFO: About to execute repetition 1 of 5 for repeatedTestWithRepetitionInfo INFO: About to execute repetition 2 of 5 for repeatedTestWithRepetitionInfo INFO: About to execute repetition 3 of 5 for repeatedTestWithRepetitionInfo INFO: About to execute repetition 4 of 5 for repeatedTestWithRepetitionInfo INFO: About to execute repetition 5 of 5 for repeatedTestWithRepetitionInfo INFO: About to execute repetition 1 of 1 for customDisplayName INFO: About to execute repetition 1 of 1 for customDisplayNameWithLongPattern INFO: About to execute repetition 1 of 5 for repeatedTestInGerman INFO: About to execute repetition 2 of 5 for repeatedTestInGerman INFO: About to execute repetition 3 of 5 for repeatedTestInGerman INFO: About to execute repetition 4 of 5 for repeatedTestInGerman INFO: About to execute repetition 5 of 5 for repeatedTestInGerman
import static org . junit . jupiter . api . Assertions . assertEquals ; import java.util.logging.Logger ; import org.junit.jupiter.api.BeforeEach ; import org.junit.jupiter.api.DisplayName ; import org.junit.jupiter.api.RepeatedTest ; import org.junit.jupiter.api.RepetitionInfo ; import org.junit.jupiter.api.TestInfo ; class RepeatedTestsDemo { private Logger logger = // ... @BeforeEach void beforeEach ( TestInfo testInfo , RepetitionInfo repetitionInfo ) { int currentRepetition = repetitionInfo . getCurrentRepetition (); int totalRepetitions = repetitionInfo . getTotalRepetitions (); String methodName = testInfo . getTestMethod (). get (). getName (); logger . info ( String . format ( "About to execute repetition %d of %d for %s" , // currentRepetition , totalRepetitions , methodName )); } @RepeatedTest ( 10 ) void repeatedTest () { // ... } @RepeatedTest ( 5 ) void repeatedTestWithRepetitionInfo ( RepetitionInfo repetitionInfo ) { assertEquals ( 5 , repetitionInfo . getTotalRepetitions ()); } @RepeatedTest ( value = 1 , name = "{displayName} {currentRepetition}/{totalRepetitions}" ) @DisplayName ( "Repeat!" ) void customDisplayName ( TestInfo testInfo ) { assertEquals ( "Repeat! 1/1" , testInfo . getDisplayName ()); } @RepeatedTest ( value = 1 , name = RepeatedTest . LONG_DISPLAY_NAME ) @DisplayName ( "Details..." ) void customDisplayNameWithLongPattern ( TestInfo testInfo ) { assertEquals ( "Details... :: repetition 1 of 1" , testInfo . getDisplayName ()); } @RepeatedTest ( value = 5 , name = "Wiederholung {currentRepetition} von {totalRepetitions}" ) void repeatedTestInGerman () { // ... } } When using the ConsoleLauncher with the unicode theme enabled, execution of RepeatedTestsDemo results in the following output to the console.
├─ RepeatedTestsDemo ✔ │ ├─ repeatedTest() ✔ │ │ ├─ repetition 1 of 10 ✔ │ │ ├─ repetition 2 of 10 ✔ │ │ ├─ repetition 3 of 10 ✔ │ │ ├─ repetition 4 of 10 ✔ │ │ ├─ repetition 5 of 10 ✔ │ │ ├─ repetition 6 of 10 ✔ │ │ ├─ repetition 7 of 10 ✔ │ │ ├─ repetition 8 of 10 ✔ │ │ ├─ repetition 9 of 10 ✔ │ │ └─ repetition 10 of 10 ✔ │ ├─ repeatedTestWithRepetitionInfo(RepetitionInfo) ✔ │ │ ├─ repetition 1 of 5 ✔ │ │ ├─ repetition 2 of 5 ✔ │ │ ├─ repetition 3 of 5 ✔ │ │ ├─ repetition 4 of 5 ✔ │ │ └─ repetition 5 of 5 ✔ │ ├─ Repeat! ✔ │ │ └─ Repeat! 1/1 ✔ │ ├─ Details... ✔ │ │ └─ Details... :: repetition 1 of 1 ✔ │ └─ repeatedTestInGerman() ✔ │ ├─ Wiederholung 1 von 5 ✔ │ ├─ Wiederholung 2 von 5 ✔ │ ├─ Wiederholung 3 von 5 ✔ │ ├─ Wiederholung 4 von 5 ✔ │ └─ Wiederholung 5 von 5 ✔
2.15. Parameterized Tests
Parameterized tests make it possible to run a test multiple times with different arguments. They are declared just like regular @Test methods but use the @ParameterizedTest annotation instead. In addition, you must declare at least one source that will provide the arguments for each invocation and then consume the arguments in the test method.
The following example demonstrates a parameterized test that uses the @ValueSource annotation to specify a String array as the source of arguments.
@ParameterizedTest @ValueSource ( strings = { "racecar" , "radar" , "able was I ere I saw elba" }) void palindromes ( String candidate ) { assertTrue ( StringUtils . isPalindrome ( candidate )); } When executing the above parameterized test method, each invocation will be reported separately. For instance, the ConsoleLauncher will print output similar to the following.
palindromes(String) ✔ ├─ [1] candidate=racecar ✔ ├─ [2] candidate=radar ✔ └─ [3] candidate=able was I ere I saw elba ✔
2.15.1. Required Setup
In order to use parameterized tests you need to add a dependency on the junit-jupiter-params artifact. Please refer to Dependency Metadata for details.
2.15.2. Consuming Arguments
Parameterized test methods typically consume arguments directly from the configured source (see Sources of Arguments) following a one-to-one correlation between argument source index and method parameter index (see examples in @CsvSource). However, a parameterized test method may also choose to aggregate arguments from the source into a single object passed to the method (see Argument Aggregation). Additional arguments may also be provided by a ParameterResolver (e.g., to obtain an instance of TestInfo, TestReporter, etc.). Specifically, a parameterized test method must declare formal parameters according to the following rules.
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Zero or more indexed arguments must be declared first.
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Zero or more aggregators must be declared next.
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Zero or more arguments supplied by a
ParameterResolvermust be declared last.
In this context, an indexed argument is an argument for a given index in the Arguments provided by an ArgumentsProvider that is passed as an argument to the parameterized method at the same index in the method's formal parameter list. An aggregator is any parameter of type ArgumentsAccessor or any parameter annotated with @AggregateWith.
| AutoCloseable arguments Arguments that implement To prevent this from happening, set the |
2.15.3. Sources of Arguments
Out of the box, JUnit Jupiter provides quite a few source annotations. Each of the following subsections provides a brief overview and an example for each of them. Please refer to the Javadoc in the org.junit.jupiter.params.provider package for additional information.
@ValueSource
@ValueSource is one of the simplest possible sources. It lets you specify a single array of literal values and can only be used for providing a single argument per parameterized test invocation.
The following types of literal values are supported by @ValueSource.
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short -
byte -
int -
long -
float -
double -
char -
boolean -
java.lang.String -
java.lang.Class
For example, the following @ParameterizedTest method will be invoked three times, with the values 1, 2, and 3 respectively.
@ParameterizedTest @ValueSource ( ints = { 1 , 2 , 3 }) void testWithValueSource ( int argument ) { assertTrue ( argument > 0 && argument < 4 ); } Null and Empty Sources
In order to check corner cases and verify proper behavior of our software when it is supplied bad input, it can be useful to have null and empty values supplied to our parameterized tests. The following annotations serve as sources of null and empty values for parameterized tests that accept a single argument.
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@NullSource: provides a singlenullargument to the annotated@ParameterizedTestmethod.-
@NullSourcecannot be used for a parameter that has a primitive type.
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@EmptySource: provides a single empty argument to the annotated@ParameterizedTestmethod for parameters of the following types:java.lang.String,java.util.List,java.util.Set,java.util.Map, primitive arrays (e.g.,int[],char[][], etc.), object arrays (e.g.,String[],Integer[][], etc.).-
Subtypes of the supported types are not supported.
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@NullAndEmptySource: a composed annotation that combines the functionality of@NullSourceand@EmptySource.
If you need to supply multiple varying types of blank strings to a parameterized test, you can achieve that using @ValueSource — for example, @ValueSource(strings = {" ", " ", "\t", "\n"}).
You can also combine @NullSource, @EmptySource, and @ValueSource to test a wider range of null, empty, and blank input. The following example demonstrates how to achieve this for strings.
@ParameterizedTest @NullSource @EmptySource @ValueSource ( strings = { " " , " " , "\t" , "\n" }) void nullEmptyAndBlankStrings ( String text ) { assertTrue ( text == null || text . trim (). isEmpty ()); } Making use of the composed @NullAndEmptySource annotation simplifies the above as follows.
@ParameterizedTest @NullAndEmptySource @ValueSource ( strings = { " " , " " , "\t" , "\n" }) void nullEmptyAndBlankStrings ( String text ) { assertTrue ( text == null || text . trim (). isEmpty ()); } Both variants of the nullEmptyAndBlankStrings(String) parameterized test method result in six invocations: 1 for null, 1 for the empty string, and 4 for the explicit blank strings supplied via @ValueSource. |
@EnumSource
@EnumSource provides a convenient way to use Enum constants.
@ParameterizedTest @EnumSource ( ChronoUnit . class ) void testWithEnumSource ( TemporalUnit unit ) { assertNotNull ( unit ); } The annotation's value attribute is optional. When omitted, the declared type of the first method parameter is used. The test will fail if it does not reference an enum type. Thus, the value attribute is required in the above example because the method parameter is declared as TemporalUnit, i.e. the interface implemented by ChronoUnit, which isn't an enum type. Changing the method parameter type to ChronoUnit allows you to omit the explicit enum type from the annotation as follows.
@ParameterizedTest @EnumSource void testWithEnumSourceWithAutoDetection ( ChronoUnit unit ) { assertNotNull ( unit ); } The annotation provides an optional names attribute that lets you specify which constants shall be used, like in the following example. If omitted, all constants will be used.
@ParameterizedTest @EnumSource ( names = { "DAYS" , "HOURS" }) void testWithEnumSourceInclude ( ChronoUnit unit ) { assertTrue ( EnumSet . of ( ChronoUnit . DAYS , ChronoUnit . HOURS ). contains ( unit )); } The @EnumSource annotation also provides an optional mode attribute that enables fine-grained control over which constants are passed to the test method. For example, you can exclude names from the enum constant pool or specify regular expressions as in the following examples.
@ParameterizedTest @EnumSource ( mode = EXCLUDE , names = { "ERAS" , "FOREVER" }) void testWithEnumSourceExclude ( ChronoUnit unit ) { assertFalse ( EnumSet . of ( ChronoUnit . ERAS , ChronoUnit . FOREVER ). contains ( unit )); } @ParameterizedTest @EnumSource ( mode = MATCH_ALL , names = "^.*DAYS$" ) void testWithEnumSourceRegex ( ChronoUnit unit ) { assertTrue ( unit . name (). endsWith ( "DAYS" )); } @MethodSource
@MethodSource allows you to refer to one or more factory methods of the test class or external classes.
Factory methods within the test class must be static unless the test class is annotated with @TestInstance(Lifecycle.PER_CLASS); whereas, factory methods in external classes must always be static. In addition, such factory methods must not accept any arguments.
Each factory method must generate a stream of arguments, and each set of arguments within the stream will be provided as the physical arguments for individual invocations of the annotated @ParameterizedTest method. Generally speaking this translates to a Stream of Arguments (i.e., Stream<Arguments>); however, the actual concrete return type can take on many forms. In this context, a "stream" is anything that JUnit can reliably convert into a Stream, such as Stream, DoubleStream, LongStream, IntStream, Collection, Iterator, Iterable, an array of objects, or an array of primitives. The "arguments" within the stream can be supplied as an instance of Arguments, an array of objects (e.g., Object[]), or a single value if the parameterized test method accepts a single argument.
If you only need a single parameter, you can return a Stream of instances of the parameter type as demonstrated in the following example.
@ParameterizedTest @MethodSource ( "stringProvider" ) void testWithExplicitLocalMethodSource ( String argument ) { assertNotNull ( argument ); } static Stream < String > stringProvider () { return Stream . of ( "apple" , "banana" ); } If you do not explicitly provide a factory method name via @MethodSource, JUnit Jupiter will search for a factory method that has the same name as the current @ParameterizedTest method by convention. This is demonstrated in the following example.
@ParameterizedTest @MethodSource void testWithDefaultLocalMethodSource ( String argument ) { assertNotNull ( argument ); } static Stream < String > testWithDefaultLocalMethodSource () { return Stream . of ( "apple" , "banana" ); } Streams for primitive types (DoubleStream, IntStream, and LongStream) are also supported as demonstrated by the following example.
@ParameterizedTest @MethodSource ( "range" ) void testWithRangeMethodSource ( int argument ) { assertNotEquals ( 9 , argument ); } static IntStream range () { return IntStream . range ( 0 , 20 ). skip ( 10 ); } If a parameterized test method declares multiple parameters, you need to return a collection, stream, or array of Arguments instances or object arrays as shown below (see the Javadoc for @MethodSource for further details on supported return types). Note that arguments(Object…) is a static factory method defined in the Arguments interface. In addition, Arguments.of(Object…) may be used as an alternative to arguments(Object…).
@ParameterizedTest @MethodSource ( "stringIntAndListProvider" ) void testWithMultiArgMethodSource ( String str , int num , List < String > list ) { assertEquals ( 5 , str . length ()); assertTrue ( num >= 1 && num <= 2 ); assertEquals ( 2 , list . size ()); } static Stream < Arguments > stringIntAndListProvider () { return Stream . of ( arguments ( "apple" , 1 , Arrays . asList ( "a" , "b" )), arguments ( "lemon" , 2 , Arrays . asList ( "x" , "y" )) ); } An external, static factory method can be referenced by providing its fully qualified method name as demonstrated in the following example.
package example ; import java.util.stream.Stream ; import org.junit.jupiter.params.ParameterizedTest ; import org.junit.jupiter.params.provider.MethodSource ; class ExternalMethodSourceDemo { @ParameterizedTest @MethodSource ( "example.StringsProviders#tinyStrings" ) void testWithExternalMethodSource ( String tinyString ) { // test with tiny string } } class StringsProviders { static Stream < String > tinyStrings () { return Stream . of ( "." , "oo" , "OOO" ); } } @CsvSource
@CsvSource allows you to express argument lists as comma-separated values (i.e., CSV String literals). Each string provided via the value attribute in @CsvSource represents a CSV line and results in one invocation of the parameterized test.
@ParameterizedTest @CsvSource ({ "apple, 1" , "banana, 2" , "'lemon, lime', 0xF1" , "strawberry, 700_000" }) void testWithCsvSource ( String fruit , int rank ) { assertNotNull ( fruit ); assertNotEquals ( 0 , rank ); } If the programming language you are using supports text blocks — for example, Java SE 15 or higher — you can alternatively use the textBlock attribute of @CsvSource. Each line within a text block represents a CSV line and results in one invocation of the parameterized test. Using a text block, the previous example can be implemented as follows.
@ParameterizedTest @CsvSource ( textBlock = """ apple, 1 banana, 2 'lemon, lime', 0xF1 strawberry, 700_000 """ ) void testWithCsvSource ( String fruit , int rank ) { // ... } The default delimiter is a comma (,), but you can use another character by setting the delimiter attribute. Alternatively, the delimiterString attribute allows you to use a String delimiter instead of a single character. However, both delimiter attributes cannot be set simultaneously.
@CsvSource uses a single quote ' as its quote character. See the 'lemon, lime' value in the example above and in the table below. An empty, quoted value '' results in an empty String unless the emptyValue attribute is set; whereas, an entirely empty value is interpreted as a null reference. By specifying one or more nullValues, a custom value can be interpreted as a null reference (see the NIL example in the table below). An ArgumentConversionException is thrown if the target type of a null reference is a primitive type.
An unquoted empty value will always be converted to a null reference regardless of any custom values configured via the nullValues attribute. |
Unless it starts with a quote character, leading and trailing whitespace in a CSV column is trimmed by default. This behavior can be changed by setting the ignoreLeadingAndTrailingWhitespace attribute to true.
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@CsvFileSource
@CsvFileSource lets you use comma-separated value (CSV) files from the classpath or the local file system. Each line from a CSV file results in one invocation of the parameterized test.
The default delimiter is a comma (,), but you can use another character by setting the delimiter attribute. Alternatively, the delimiterString attribute allows you to use a String delimiter instead of a single character. However, both delimiter attributes cannot be set simultaneously.
| Comments in CSV files Any line beginning with a# symbol will be interpreted as a comment and will be ignored. |
@ParameterizedTest @CsvFileSource ( resources = "/two-column.csv" , numLinesToSkip = 1 ) void testWithCsvFileSourceFromClasspath ( String country , int reference ) { assertNotNull ( country ); assertNotEquals ( 0 , reference ); } @ParameterizedTest @CsvFileSource ( files = "src/test/resources/two-column.csv" , numLinesToSkip = 1 ) void testWithCsvFileSourceFromFile ( String country , int reference ) { assertNotNull ( country ); assertNotEquals ( 0 , reference ); } two-column.csv
Country, reference Sweden, 1 Poland, 2 "United States of America", 3 France, 700_000 In contrast to the syntax used in @CsvSource, @CsvFileSource uses a double quote " as the quote character. See the "United States of America" value in the example above. An empty, quoted value "" results in an empty String unless the emptyValue attribute is set; whereas, an entirely empty value is interpreted as a null reference. By specifying one or more nullValues, a custom value can be interpreted as a null reference. An ArgumentConversionException is thrown if the target type of a null reference is a primitive type.
An unquoted empty value will always be converted to a null reference regardless of any custom values configured via the nullValues attribute. |
Unless it starts with a quote character, leading and trailing whitespace in a CSV column is trimmed by default. This behavior can be changed by setting the ignoreLeadingAndTrailingWhitespace attribute to true.
@ArgumentsSource
@ArgumentsSource can be used to specify a custom, reusable ArgumentsProvider. Note that an implementation of ArgumentsProvider must be declared as either a top-level class or as a static nested class.
@ParameterizedTest @ArgumentsSource ( MyArgumentsProvider . class ) void testWithArgumentsSource ( String argument ) { assertNotNull ( argument ); } public class MyArgumentsProvider implements ArgumentsProvider { @Override public Stream <? extends Arguments > provideArguments ( ExtensionContext context ) { return Stream . of ( "apple" , "banana" ). map ( Arguments: : of ); } } 2.15.4. Argument Conversion
Widening Conversion
JUnit Jupiter supports Widening Primitive Conversion for arguments supplied to a @ParameterizedTest. For example, a parameterized test annotated with @ValueSource(ints = { 1, 2, 3 }) can be declared to accept not only an argument of type int but also an argument of type long, float, or double.
Implicit Conversion
To support use cases like @CsvSource, JUnit Jupiter provides a number of built-in implicit type converters. The conversion process depends on the declared type of each method parameter.
For example, if a @ParameterizedTest declares a parameter of type TimeUnit and the actual type supplied by the declared source is a String, the string will be automatically converted into the corresponding TimeUnit enum constant.
@ParameterizedTest @ValueSource ( strings = "SECONDS" ) void testWithImplicitArgumentConversion ( ChronoUnit argument ) { assertNotNull ( argument . name ()); } String instances are implicitly converted to the following target types.
Decimal, hexadecimal, and octal String literals will be converted to their integral types: byte, short, int, long, and their boxed counterparts. |
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Fallback String-to-Object Conversion
In addition to implicit conversion from strings to the target types listed in the above table, JUnit Jupiter also provides a fallback mechanism for automatic conversion from a String to a given target type if the target type declares exactly one suitable factory method or a factory constructor as defined below.
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factory method: a non-private,
staticmethod declared in the target type that accepts a singleStringargument and returns an instance of the target type. The name of the method can be arbitrary and need not follow any particular convention. -
factory constructor: a non-private constructor in the target type that accepts a single
Stringargument. Note that the target type must be declared as either a top-level class or as astaticnested class.
| If multiple factory methods are discovered, they will be ignored. If a factory method and a factory constructor are discovered, the factory method will be used instead of the constructor. |
For example, in the following @ParameterizedTest method, the Book argument will be created by invoking the Book.fromTitle(String) factory method and passing "42 Cats" as the title of the book.
@ParameterizedTest @ValueSource ( strings = "42 Cats" ) void testWithImplicitFallbackArgumentConversion ( Book book ) { assertEquals ( "42 Cats" , book . getTitle ()); } public class Book { private final String title ; private Book ( String title ) { this . title = title ; } public static Book fromTitle ( String title ) { return new Book ( title ); } public String getTitle () { return this . title ; } } Explicit Conversion
Instead of relying on implicit argument conversion you may explicitly specify an ArgumentConverter to use for a certain parameter using the @ConvertWith annotation like in the following example. Note that an implementation of ArgumentConverter must be declared as either a top-level class or as a static nested class.
@ParameterizedTest @EnumSource ( ChronoUnit . class ) void testWithExplicitArgumentConversion ( @ConvertWith ( ToStringArgumentConverter . class ) String argument ) { assertNotNull ( ChronoUnit . valueOf ( argument )); } public class ToStringArgumentConverter extends SimpleArgumentConverter { @Override protected Object convert ( Object source , Class <?> targetType ) { assertEquals ( String . class , targetType , "Can only convert to String" ); if ( source instanceof Enum <?>) { return (( Enum <?>) source ). name (); } return String . valueOf ( source ); } } If the converter is only meant to convert one type to another, you can extend TypedArgumentConverter to avoid boilerplate type checks.
public class ToLengthArgumentConverter extends TypedArgumentConverter < String , Integer > { protected ToLengthArgumentConverter () { super ( String . class , Integer . class ); } @Override protected Integer convert ( String source ) { return ( source != null ? source . length () : 0 ); } } Explicit argument converters are meant to be implemented by test and extension authors. Thus, junit-jupiter-params only provides a single explicit argument converter that may also serve as a reference implementation: JavaTimeArgumentConverter. It is used via the composed annotation JavaTimeConversionPattern.
@ParameterizedTest @ValueSource ( strings = { "01.01.2017" , "31.12.2017" }) void testWithExplicitJavaTimeConverter ( @JavaTimeConversionPattern ( "dd.MM.yyyy" ) LocalDate argument ) { assertEquals ( 2017 , argument . getYear ()); } 2.15.5. Argument Aggregation
By default, each argument provided to a @ParameterizedTest method corresponds to a single method parameter. Consequently, argument sources which are expected to supply a large number of arguments can lead to large method signatures.
In such cases, an ArgumentsAccessor can be used instead of multiple parameters. Using this API, you can access the provided arguments through a single argument passed to your test method. In addition, type conversion is supported as discussed in Implicit Conversion.
@ParameterizedTest @CsvSource ({ "Jane, Doe, F, 1990-05-20" , "John, Doe, M, 1990-10-22" }) void testWithArgumentsAccessor ( ArgumentsAccessor arguments ) { Person person = new Person ( arguments . getString ( 0 ), arguments . getString ( 1 ), arguments . get ( 2 , Gender . class ), arguments . get ( 3 , LocalDate . class )); if ( person . getFirstName (). equals ( "Jane" )) { assertEquals ( Gender . F , person . getGender ()); } else { assertEquals ( Gender . M , person . getGender ()); } assertEquals ( "Doe" , person . getLastName ()); assertEquals ( 1990 , person . getDateOfBirth (). getYear ()); } An instance of ArgumentsAccessor is automatically injected into any parameter of type ArgumentsAccessor.
Custom Aggregators
Apart from direct access to a @ParameterizedTest method's arguments using an ArgumentsAccessor, JUnit Jupiter also supports the usage of custom, reusable aggregators.
To use a custom aggregator, implement the ArgumentsAggregator interface and register it via the @AggregateWith annotation on a compatible parameter in the @ParameterizedTest method. The result of the aggregation will then be provided as an argument for the corresponding parameter when the parameterized test is invoked. Note that an implementation of ArgumentsAggregator must be declared as either a top-level class or as a static nested class.
@ParameterizedTest @CsvSource ({ "Jane, Doe, F, 1990-05-20" , "John, Doe, M, 1990-10-22" }) void testWithArgumentsAggregator ( @AggregateWith ( PersonAggregator . class ) Person person ) { // perform assertions against person } public class PersonAggregator implements ArgumentsAggregator { @Override public Person aggregateArguments ( ArgumentsAccessor arguments , ParameterContext context ) { return new Person ( arguments . getString ( 0 ), arguments . getString ( 1 ), arguments . get ( 2 , Gender . class ), arguments . get ( 3 , LocalDate . class )); } } If you find yourself repeatedly declaring @AggregateWith(MyTypeAggregator.class) for multiple parameterized test methods across your codebase, you may wish to create a custom composed annotation such as @CsvToMyType that is meta-annotated with @AggregateWith(MyTypeAggregator.class). The following example demonstrates this in action with a custom @CsvToPerson annotation.
@ParameterizedTest @CsvSource ({ "Jane, Doe, F, 1990-05-20" , "John, Doe, M, 1990-10-22" }) void testWithCustomAggregatorAnnotation ( @CsvToPerson Person person ) { // perform assertions against person } @Retention ( RetentionPolicy . RUNTIME ) @Target ( ElementType . PARAMETER ) @AggregateWith ( PersonAggregator . class ) public @interface CsvToPerson { } 2.15.6. Customizing Display Names
By default, the display name of a parameterized test invocation contains the invocation index and the String representation of all arguments for that specific invocation. Each of them is preceded by the parameter name (unless the argument is only available via an ArgumentsAccessor or ArgumentAggregator), if present in the bytecode (for Java, test code must be compiled with the -parameters compiler flag).
However, you can customize invocation display names via the name attribute of the @ParameterizedTest annotation like in the following example.
@DisplayName ( "Display name of container" ) @ParameterizedTest ( name = "{index} ==> the rank of ''{0}'' is {1}" ) @CsvSource ({ "apple, 1" , "banana, 2" , "'lemon, lime', 3" }) void testWithCustomDisplayNames ( String fruit , int rank ) { } When executing the above method using the ConsoleLauncher you will see output similar to the following.
Display name of container ✔ ├─ 1 ==> the rank of 'apple' is 1 ✔ ├─ 2 ==> the rank of 'banana' is 2 ✔ └─ 3 ==> the rank of 'lemon, lime' is 3 ✔
Please note that name is a MessageFormat pattern. Thus, a single quote (') needs to be represented as a doubled single quote ('') in order to be displayed.
The following placeholders are supported within custom display names.
| Placeholder | Description |
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| | the display name of the method |
| | the current invocation index (1-based) |
| | the complete, comma-separated arguments list |
| | the complete, comma-separated arguments list with parameter names |
| | an individual argument |
When including arguments in display names, their string representations are truncated if they exceed the configured maximum length. The limit is configurable via the junit.jupiter.params.displayname.argument.maxlength configuration parameter and defaults to 512 characters. |
When using @MethodSource or @ArgumentSource, you can give names to arguments. This name will be used if the argument is included in the invocation display name, like in the example below.
@DisplayName ( "A parameterized test with named arguments" ) @ParameterizedTest ( name = "{index}: {0}" ) @MethodSource ( "namedArguments" ) void testWithNamedArguments ( File file ) { } static Stream < Arguments > namedArguments () { return Stream . of ( arguments ( Named . of ( "An important file" , new File ( "path1" ))), arguments ( Named . of ( "Another file" , new File ( "path2" )))); } A parameterized test with named arguments ✔ ├─ 1: An important file ✔ └─ 2: Another file ✔
If you'd like to set default name pattern for all parameterized tests in your project, you can add the following configuration to junit-platform.properties
junit.jupiter.params.displayname.default = {index} the display name for a parameterized method is determined according to the following precedence rules:
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nameof@ParameterizedTest, if present -
the value of
junit.jupiter.params.displayname.default(from junit-platform.properties), if present -
DEFAULT_DISPLAY_NAMEconstant defined in@ParameterizedTest
2.15.7. Lifecycle and Interoperability
Each invocation of a parameterized test has the same lifecycle as a regular @Test method. For example, @BeforeEach methods will be executed before each invocation. Similar to Dynamic Tests, invocations will appear one by one in the test tree of an IDE. You may at will mix regular @Test methods and @ParameterizedTest methods within the same test class.
You may use ParameterResolver extensions with @ParameterizedTest methods. However, method parameters that are resolved by argument sources need to come first in the argument list. Since a test class may contain regular tests as well as parameterized tests with different parameter lists, values from argument sources are not resolved for lifecycle methods (e.g. @BeforeEach) and test class constructors.
@BeforeEach void beforeEach ( TestInfo testInfo ) { // ... } @ParameterizedTest @ValueSource ( strings = "apple" ) void testWithRegularParameterResolver ( String argument , TestReporter testReporter ) { testReporter . publishEntry ( "argument" , argument ); } @AfterEach void afterEach ( TestInfo testInfo ) { // ... } 2.16. Test Templates
A @TestTemplate method is not a regular test case but rather a template for test cases. As such, it is designed to be invoked multiple times depending on the number of invocation contexts returned by the registered providers. Thus, it must be used in conjunction with a registered TestTemplateInvocationContextProvider extension. Each invocation of a test template method behaves like the execution of a regular @Test method with full support for the same lifecycle callbacks and extensions. Please refer to Providing Invocation Contexts for Test Templates for usage examples.
| Repeated Tests and Parameterized Tests are built-in specializations of test templates. |
2.17. Dynamic Tests
The standard @Test annotation in JUnit Jupiter described in Annotations is very similar to the @Test annotation in JUnit 4. Both describe methods that implement test cases. These test cases are static in the sense that they are fully specified at compile time, and their behavior cannot be changed by anything happening at runtime. Assumptions provide a basic form of dynamic behavior but are intentionally rather limited in their expressiveness.
In addition to these standard tests a completely new kind of test programming model has been introduced in JUnit Jupiter. This new kind of test is a dynamic test which is generated at runtime by a factory method that is annotated with @TestFactory.
In contrast to @Test methods, a @TestFactory method is not itself a test case but rather a factory for test cases. Thus, a dynamic test is the product of a factory. Technically speaking, a @TestFactory method must return a single DynamicNode or a Stream, Collection, Iterable, Iterator, or array of DynamicNode instances. Instantiable subclasses of DynamicNode are DynamicContainer and DynamicTest. DynamicContainer instances are composed of a display name and a list of dynamic child nodes, enabling the creation of arbitrarily nested hierarchies of dynamic nodes. DynamicTest instances will be executed lazily, enabling dynamic and even non-deterministic generation of test cases.
Any Stream returned by a @TestFactory will be properly closed by calling stream.close(), making it safe to use a resource such as Files.lines().
As with @Test methods, @TestFactory methods must not be private or static and may optionally declare parameters to be resolved by ParameterResolvers.
A DynamicTest is a test case generated at runtime. It is composed of a display name and an Executable. Executable is a @FunctionalInterface which means that the implementations of dynamic tests can be provided as lambda expressions or method references.
| Dynamic Test Lifecycle The execution lifecycle of a dynamic test is quite different than it is for a standard@Test case. Specifically, there are no lifecycle callbacks for individual dynamic tests. This means that @BeforeEach and @AfterEach methods and their corresponding extension callbacks are executed for the @TestFactory method but not for each dynamic test. In other words, if you access fields from the test instance within a lambda expression for a dynamic test, those fields will not be reset by callback methods or extensions between the execution of individual dynamic tests generated by the same @TestFactory method. |
As of JUnit Jupiter 5.8.1, dynamic tests must always be created by factory methods; however, this might be complemented by a registration facility in a later release.
2.17.1. Dynamic Test Examples
The following DynamicTestsDemo class demonstrates several examples of test factories and dynamic tests.
The first method returns an invalid return type. Since an invalid return type cannot be detected at compile time, a JUnitException is thrown when it is detected at runtime.
The next six methods are very simple examples that demonstrate the generation of a Collection, Iterable, Iterator, array, or Stream of DynamicTest instances. Most of these examples do not really exhibit dynamic behavior but merely demonstrate the supported return types in principle. However, dynamicTestsFromStream() and dynamicTestsFromIntStream() demonstrate how easy it is to generate dynamic tests for a given set of strings or a range of input numbers.
The next method is truly dynamic in nature. generateRandomNumberOfTests() implements an Iterator that generates random numbers, a display name generator, and a test executor and then provides all three to DynamicTest.stream(). Although the non-deterministic behavior of generateRandomNumberOfTests() is of course in conflict with test repeatability and should thus be used with care, it serves to demonstrate the expressiveness and power of dynamic tests.
The next method is similar to generateRandomNumberOfTests() in terms of flexibility; however, dynamicTestsFromStreamFactoryMethod() generates a stream of dynamic tests from an existing Stream via the DynamicTest.stream() factory method.
For demonstration purposes, the dynamicNodeSingleTest() method generates a single DynamicTest instead of a stream, and the dynamicNodeSingleContainer() method generates a nested hierarchy of dynamic tests utilizing DynamicContainer.
import static example . util . StringUtils . isPalindrome ; import static org . junit . jupiter . api . Assertions . assertEquals ; import static org . junit . jupiter . api . Assertions . assertFalse ; import static org . junit . jupiter . api . Assertions . assertNotNull ; import static org . junit . jupiter . api . Assertions . assertTrue ; import static org . junit . jupiter . api . DynamicContainer . dynamicContainer ; import static org . junit . jupiter . api . DynamicTest . dynamicTest ; import static org . junit . jupiter . api . Named . named ; import java.util.Arrays ; import java.util.Collection ; import java.util.Iterator ; import java.util.List ; import java.util.Random ; import java.util.function.Function ; import java.util.stream.IntStream ; import java.util.stream.Stream ; import example.util.Calculator ; import org.junit.jupiter.api.DynamicNode ; import org.junit.jupiter.api.DynamicTest ; import org.junit.jupiter.api.Named ; import org.junit.jupiter.api.Tag ; import org.junit.jupiter.api.TestFactory ; import org.junit.jupiter.api.function.ThrowingConsumer ; class DynamicTestsDemo { private final Calculator calculator = new Calculator (); // This will result in a JUnitException! @TestFactory List < String > dynamicTestsWithInvalidReturnType () { return Arrays . asList ( "Hello" ); } @TestFactory Collection < DynamicTest > dynamicTestsFromCollection () { return Arrays . asList ( dynamicTest ( "1st dynamic test" , () -> assertTrue ( isPalindrome ( "madam" ))), dynamicTest ( "2nd dynamic test" , () -> assertEquals ( 4 , calculator . multiply ( 2 , 2 ))) ); } @TestFactory Iterable < DynamicTest > dynamicTestsFromIterable () { return Arrays . asList ( dynamicTest ( "3rd dynamic test" , () -> assertTrue ( isPalindrome ( "madam" ))), dynamicTest ( "4th dynamic test" , () -> assertEquals ( 4 , calculator . multiply ( 2 , 2 ))) ); } @TestFactory Iterator < DynamicTest > dynamicTestsFromIterator () { return Arrays . asList ( dynamicTest ( "5th dynamic test" , () -> assertTrue ( isPalindrome ( "madam" ))), dynamicTest ( "6th dynamic test" , () -> assertEquals ( 4 , calculator . multiply ( 2 , 2 ))) ). iterator (); } @TestFactory DynamicTest [] dynamicTestsFromArray () { return new DynamicTest [] { dynamicTest ( "7th dynamic test" , () -> assertTrue ( isPalindrome ( "madam" ))), dynamicTest ( "8th dynamic test" , () -> assertEquals ( 4 , calculator . multiply ( 2 , 2 ))) }; } @TestFactory Stream < DynamicTest > dynamicTestsFromStream () { return Stream . of ( "racecar" , "radar" , "mom" , "dad" ) . map ( text -> dynamicTest ( text , () -> assertTrue ( isPalindrome ( text )))); } @TestFactory Stream < DynamicTest > dynamicTestsFromIntStream () { // Generates tests for the first 10 even integers. return IntStream . iterate ( 0 , n -> n + 2 ). limit ( 10 ) . mapToObj ( n -> dynamicTest ( "test" + n , () -> assertTrue ( n % 2 == 0 ))); } @TestFactory Stream < DynamicTest > generateRandomNumberOfTestsFromIterator () { // Generates random positive integers between 0 and 100 until // a number evenly divisible by 7 is encountered. Iterator < Integer > inputGenerator = new Iterator < Integer >() { Random random = new Random (); int current ; @Override public boolean hasNext () { current = random . nextInt ( 100 ); return current % 7 != 0 ; } @Override public Integer next () { return current ; } }; // Generates display names like: input:5, input:37, input:85, etc. Function < Integer , String > displayNameGenerator = ( input ) -> "input:" + input ; // Executes tests based on the current input value. ThrowingConsumer < Integer > testExecutor = ( input ) -> assertTrue ( input % 7 != 0 ); // Returns a stream of dynamic tests. return DynamicTest . stream ( inputGenerator , displayNameGenerator , testExecutor ); } @TestFactory Stream < DynamicTest > dynamicTestsFromStreamFactoryMethod () { // Stream of palindromes to check Stream < String > inputStream = Stream . of ( "racecar" , "radar" , "mom" , "dad" ); // Generates display names like: racecar is a palindrome Function < String , String > displayNameGenerator = text -> text + " is a palindrome" ; // Executes tests based on the current input value. ThrowingConsumer < String > testExecutor = text -> assertTrue ( isPalindrome ( text )); // Returns a stream of dynamic tests. return DynamicTest . stream ( inputStream , displayNameGenerator , testExecutor ); } @TestFactory Stream < DynamicTest > dynamicTestsFromStreamFactoryMethodWithNames () { // Stream of palindromes to check Stream < Named < String >> inputStream = Stream . of ( named ( "racecar is a palindrome" , "racecar" ), named ( "radar is also a palindrome" , "radar" ), named ( "mom also seems to be a palindrome" , "mom" ), named ( "dad is yet another palindrome" , "dad" ) ); // Returns a stream of dynamic tests. return DynamicTest . stream ( inputStream , text -> assertTrue ( isPalindrome ( text ))); } @TestFactory Stream < DynamicNode > dynamicTestsWithContainers () { return Stream . of ( "A" , "B" , "C" ) . map ( input -> dynamicContainer ( "Container " + input , Stream . of ( dynamicTest ( "not null" , () -> assertNotNull ( input )), dynamicContainer ( "properties" , Stream . of ( dynamicTest ( "length > 0" , () -> assertTrue ( input . length () > 0 )), dynamicTest ( "not empty" , () -> assertFalse ( input . isEmpty ())) )) ))); } @TestFactory DynamicNode dynamicNodeSingleTest () { return dynamicTest ( "'pop' is a palindrome" , () -> assertTrue ( isPalindrome ( "pop" ))); } @TestFactory DynamicNode dynamicNodeSingleContainer () { return dynamicContainer ( "palindromes" , Stream . of ( "racecar" , "radar" , "mom" , "dad" ) . map ( text -> dynamicTest ( text , () -> assertTrue ( isPalindrome ( text ))) )); } } 2.17.2. URI Test Sources for Dynamic Tests
The JUnit Platform provides TestSource, a representation of the source of a test or container used to navigate to its location by IDEs and build tools.
The TestSource for a dynamic test or dynamic container can be constructed from a java.net.URI which can be supplied via the DynamicTest.dynamicTest(String, URI, Executable) or DynamicContainer.dynamicContainer(String, URI, Stream) factory method, respectively. The URI will be converted to one of the following TestSource implementations.
-
ClasspathResourceSource -
If the
URIcontains theclasspathscheme — for example,classpath:/test/foo.xml?line=20,column=2. -
DirectorySource -
If the
URIrepresents a directory present in the file system. -
FileSource -
If the
URIrepresents a file present in the file system. -
MethodSource -
If the
URIcontains themethodscheme and the fully qualified method name (FQMN) — for example,method:org.junit.Foo#bar(java.lang.String, java.lang.String[]). Please refer to the Javadoc forDiscoverySelectors.selectMethod(String)for the supported formats for a FQMN. -
ClassSource -
If the
URIcontains theclassscheme and the fully qualified class name — for example,class:org.junit.Foo?line=42. -
UriSource -
If none of the above
TestSourceimplementations are applicable.
2.18. Timeouts
The @Timeout annotation allows one to declare that a test, test factory, test template, or lifecycle method should fail if its execution time exceeds a given duration. The time unit for the duration defaults to seconds but is configurable.
The following example shows how @Timeout is applied to lifecycle and test methods.
class TimeoutDemo { @BeforeEach @Timeout ( 5 ) void setUp () { // fails if execution time exceeds 5 seconds } @Test @Timeout ( value = 100 , unit = TimeUnit . MILLISECONDS ) void failsIfExecutionTimeExceeds100Milliseconds () { // fails if execution time exceeds 100 milliseconds } } Contrary to the assertTimeoutPreemptively() assertion, the execution of the annotated method proceeds in the main thread of the test. If the timeout is exceeded, the main thread is interrupted from another thread. This is done to ensure interoperability with frameworks such as Spring that make use of mechanisms that are sensitive to the currently running thread — for example, ThreadLocal transaction management.
To apply the same timeout to all test methods within a test class and all of its @Nested classes, you can declare the @Timeout annotation at the class level. It will then be applied to all test, test factory, and test template methods within that class and its @Nested classes unless overridden by a @Timeout annotation on a specific method or @Nested class. Please note that @Timeout annotations declared at the class level are not applied to lifecycle methods.
Declaring @Timeout on a @TestFactory method checks that the factory method returns within the specified duration but does not verify the execution time of each individual DynamicTest generated by the factory. Please use assertTimeout() or assertTimeoutPreemptively() for that purpose.
If @Timeout is present on a @TestTemplate method — for example, a @RepeatedTest or @ParameterizedTest — each invocation will have the given timeout applied to it.
The following configuration parameters can be used to specify global timeouts for all methods of a certain category unless they or an enclosing test class is annotated with @Timeout:
-
junit.jupiter.execution.timeout.default -
Default timeout for all testable and lifecycle methods
-
junit.jupiter.execution.timeout.testable.method.default -
Default timeout for all testable methods
-
junit.jupiter.execution.timeout.test.method.default -
Default timeout for
@Testmethods -
junit.jupiter.execution.timeout.testtemplate.method.default -
Default timeout for
@TestTemplatemethods -
junit.jupiter.execution.timeout.testfactory.method.default -
Default timeout for
@TestFactorymethods -
junit.jupiter.execution.timeout.lifecycle.method.default -
Default timeout for all lifecycle methods
-
junit.jupiter.execution.timeout.beforeall.method.default -
Default timeout for
@BeforeAllmethods -
junit.jupiter.execution.timeout.beforeeach.method.default -
Default timeout for
@BeforeEachmethods -
junit.jupiter.execution.timeout.aftereach.method.default -
Default timeout for
@AfterEachmethods -
junit.jupiter.execution.timeout.afterall.method.default -
Default timeout for
@AfterAllmethods
More specific configuration parameters override less specific ones. For example, junit.jupiter.execution.timeout.test.method.default overrides junit.jupiter.execution.timeout.testable.method.default which overrides junit.jupiter.execution.timeout.default.
The values of such configuration parameters must be in the following, case-insensitive format: <number> [ns|μs|ms|s|m|h|d]. The space between the number and the unit may be omitted. Specifying no unit is equivalent to using seconds.
| Parameter value | Equivalent annotation |
|---|---|
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
2.18.1. Using @Timeout for Polling Tests
When dealing with asynchronous code, it is common to write tests that poll while waiting for something to happen before performing any assertions. In some cases you can rewrite the logic to use a CountDownLatch or another synchronization mechanism, but sometimes that is not possible — for example, if the subject under test sends a message to a channel in an external message broker and assertions cannot be performed until the message has been successfully sent through the channel. Asynchronous tests like these require some form of timeout to ensure they don't hang the test suite by executing indefinitely, as would be the case if an asynchronous message never gets successfully delivered.
By configuring a timeout for an asynchronous test that polls, you can ensure that the test does not execute indefinitely. The following example demonstrates how to achieve this with JUnit Jupiter's @Timeout annotation. This technique can be used to implement "poll until" logic very easily.
@Test @Timeout ( 5 ) // Poll at most 5 seconds void pollUntil () throws InterruptedException { while ( asynchronousResultNotAvailable ()) { Thread . sleep ( 250 ); // custom poll interval } // Obtain the asynchronous result and perform assertions } | If you need more control over polling intervals and greater flexibility with asynchronous tests, consider using a dedicated library such as Awaitility. |
2.18.2. Disable @Timeout Globally
When stepping through your code in a debug session, a fixed timeout limit may influence the result of the test, e.g. mark the test as failed although all assertions were met.
JUnit Jupiter supports the junit.jupiter.execution.timeout.mode configuration parameter to configure when timeouts are applied. There are three modes: enabled, disabled, and disabled_on_debug. The default mode is enabled. A VM runtime is considered to run in debug mode when one of its input parameters starts with -agentlib:jdwp. This heuristic is queried by the disabled_on_debug mode.
2.19. Parallel Execution
| Parallel test execution is an experimental feature You're invited to give it a try and provide feedback to the JUnit team so they can improve and eventually promote this feature. |
By default, JUnit Jupiter tests are run sequentially in a single thread. Running tests in parallel — for example, to speed up execution — is available as an opt-in feature since version 5.3. To enable parallel execution, set the junit.jupiter.execution.parallel.enabled configuration parameter to true — for example, in junit-platform.properties (see Configuration Parameters for other options).
Please note that enabling this property is only the first step required to execute tests in parallel. If enabled, test classes and methods will still be executed sequentially by default. Whether or not a node in the test tree is executed concurrently is controlled by its execution mode. The following two modes are available.
-
SAME_THREAD -
Force execution in the same thread used by the parent. For example, when used on a test method, the test method will be executed in the same thread as any
@BeforeAllor@AfterAllmethods of the containing test class. -
CONCURRENT -
Execute concurrently unless a resource lock forces execution in the same thread.
By default, nodes in the test tree use the SAME_THREAD execution mode. You can change the default by setting the junit.jupiter.execution.parallel.mode.default configuration parameter. Alternatively, you can use the @Execution annotation to change the execution mode for the annotated element and its subelements (if any) which allows you to activate parallel execution for individual test classes, one by one.
Configuration parameters to execute all tests in parallel
junit.jupiter.execution.parallel.enabled = true junit.jupiter.execution.parallel.mode.default = concurrent The default execution mode is applied to all nodes of the test tree with a few notable exceptions, namely test classes that use the Lifecycle.PER_CLASS mode or a MethodOrderer (except for MethodOrderer.Random). In the former case, test authors have to ensure that the test class is thread-safe; in the latter, concurrent execution might conflict with the configured execution order. Thus, in both cases, test methods in such test classes are only executed concurrently if the @Execution(CONCURRENT) annotation is present on the test class or method.
All nodes of the test tree that are configured with the CONCURRENT execution mode will be executed fully in parallel according to the provided configuration while observing the declarative synchronization mechanism. Please note that Capturing Standard Output/Error needs to be enabled separately.
In addition, you can configure the default execution mode for top-level classes by setting the junit.jupiter.execution.parallel.mode.classes.default configuration parameter. By combining both configuration parameters, you can configure classes to run in parallel but their methods in the same thread:
Configuration parameters to execute top-level classes in parallel but methods in same thread
junit.jupiter.execution.parallel.enabled = true junit.jupiter.execution.parallel.mode.default = same_thread junit.jupiter.execution.parallel.mode.classes.default = concurrent The opposite combination will run all methods within one class in parallel, but top-level classes will run sequentially:
Configuration parameters to execute top-level classes sequentially but their methods in parallel
junit.jupiter.execution.parallel.enabled = true junit.jupiter.execution.parallel.mode.default = concurrent junit.jupiter.execution.parallel.mode.classes.default = same_thread The following diagram illustrates how the execution of two top-level test classes A and B with two test methods per class behaves for all four combinations of junit.jupiter.execution.parallel.mode.default and junit.jupiter.execution.parallel.mode.classes.default (see labels in first column).
Default execution mode configuration combinations
If the junit.jupiter.execution.parallel.mode.classes.default configuration parameter is not explicitly set, the value for junit.jupiter.execution.parallel.mode.default will be used instead.
2.19.1. Configuration
Properties such as the desired parallelism and the maximum pool size can be configured using a ParallelExecutionConfigurationStrategy. The JUnit Platform provides two implementations out of the box: dynamic and fixed. Alternatively, you may implement a custom strategy.
To select a strategy, set the junit.jupiter.execution.parallel.config.strategy configuration parameter to one of the following options.
-
dynamic -
Computes the desired parallelism based on the number of available processors/cores multiplied by the
junit.jupiter.execution.parallel.config.dynamic.factorconfiguration parameter (defaults to1). -
fixed -
Uses the mandatory
junit.jupiter.execution.parallel.config.fixed.parallelismconfiguration parameter as the desired parallelism. -
custom -
Allows you to specify a custom
ParallelExecutionConfigurationStrategyimplementation via the mandatoryjunit.jupiter.execution.parallel.config.custom.classconfiguration parameter to determine the desired configuration.
If no configuration strategy is set, JUnit Jupiter uses the dynamic configuration strategy with a factor of 1. Consequently, the desired parallelism will be equal to the number of available processors/cores.
| Parallelism does not imply maximum number of concurrent threads JUnit Jupiter does not guarantee that the number of concurrently executing tests will not exceed the configured parallelism. For example, when using one of the synchronization mechanisms described in the next section, theForkJoinPool that is used behind the scenes may spawn additional threads to ensure execution continues with sufficient parallelism. Thus, if you require such guarantees in a test class, please use your own means of controlling concurrency. |
2.19.2. Synchronization
In addition to controlling the execution mode using the @Execution annotation, JUnit Jupiter provides another annotation-based declarative synchronization mechanism. The @ResourceLock annotation allows you to declare that a test class or method uses a specific shared resource that requires synchronized access to ensure reliable test execution. The shared resource is identified by a unique name which is a String. The name can be user-defined or one of the predefined constants in Resources: SYSTEM_PROPERTIES, SYSTEM_OUT, SYSTEM_ERR, LOCALE, or TIME_ZONE.
If the tests in the following example were run in parallel without the use of @ResourceLock, they would be flaky. Sometimes they would pass, and at other times they would fail due to the inherent race condition of writing and then reading the same JVM System Property.
When access to shared resources is declared using the @ResourceLock annotation, the JUnit Jupiter engine uses this information to ensure that no conflicting tests are run in parallel.
| Running tests in isolation If most of your test classes can be run in parallel without any synchronization but you have some test classes that need to run in isolation, you can mark the latter with the |
In addition to the String that uniquely identifies the shared resource, you may specify an access mode. Two tests that require READ access to a shared resource may run in parallel with each other but not while any other test that requires READ_WRITE access to the same shared resource is running.
@Execution ( CONCURRENT ) class SharedResourcesDemo { private Properties backup ; @BeforeEach void backup () { backup = new Properties (); backup . putAll ( System . getProperties ()); } @AfterEach void restore () { System . setProperties ( backup ); } @Test @ResourceLock ( value = SYSTEM_PROPERTIES , mode = READ ) void customPropertyIsNotSetByDefault () { assertNull ( System . getProperty ( "my.prop" )); } @Test @ResourceLock ( value = SYSTEM_PROPERTIES , mode = READ_WRITE ) void canSetCustomPropertyToApple () { System . setProperty ( "my.prop" , "apple" ); assertEquals ( "apple" , System . getProperty ( "my.prop" )); } @Test @ResourceLock ( value = SYSTEM_PROPERTIES , mode = READ_WRITE ) void canSetCustomPropertyToBanana () { System . setProperty ( "my.prop" , "banana" ); assertEquals ( "banana" , System . getProperty ( "my.prop" )); } } 2.20. Built-in Extensions
While the JUnit team encourages reusable extensions to be packaged and maintained in separate libraries, the JUnit Jupiter API artifact includes a few user-facing extension implementations that are considered so generally useful that users shouldn't have to add another dependency.
2.20.1. The TempDirectory Extension
| |
The built-in TempDirectory extension is used to create and clean up a temporary directory for an individual test or all tests in a test class. It is registered by default. To use it, annotate a field of type java.nio.file.Path or java.io.File with @TempDir or add a parameter of type java.nio.file.Path or java.io.File annotated with @TempDir to a lifecycle method or test method.
For example, the following test declares a parameter annotated with @TempDir for a single test method, creates and writes to a file in the temporary directory, and checks its content.
A test method that requires a temporary directory
@Test void writeItemsToFile ( @TempDir Path tempDir ) throws IOException { Path file = tempDir . resolve ( "test.txt" ); new ListWriter ( file ). write ( "a" , "b" , "c" ); assertEquals ( singletonList ( "a,b,c" ), Files . readAllLines ( file )); } You can inject multiple temporary directories by specifying multiple annotated parameters.
A test method that requires multiple temporary directories
@Test void copyFileFromSourceToTarget ( @TempDir Path source , @TempDir Path target ) throws IOException { Path sourceFile = source . resolve ( "test.txt" ); new ListWriter ( sourceFile ). write ( "a" , "b" , "c" ); Path targetFile = Files . copy ( sourceFile , target . resolve ( "test.txt" )); assertNotEquals ( sourceFile , targetFile ); assertEquals ( singletonList ( "a,b,c" ), Files . readAllLines ( targetFile )); } To revert to the old behavior of using a single temporary directory for the entire test class or method (depending on which level the annotation is used), you can set the junit.jupiter.tempdir.scope configuration parameter to per_context. However, please note that this option is deprecated and will be removed in a future release. |
@TempDir is not supported on constructor parameters. If you wish to retain a single reference to a temp directory across lifecycle methods and the current test method, please use field injection by annotating an instance field with @TempDir.
The following example stores a shared temporary directory in a static field. This allows the same sharedTempDir to be used in all lifecycle methods and test methods of the test class. For better isolation, you should use an instance field so that each test method uses a separate directory.
A test class that shares a temporary directory across test methods
class SharedTempDirectoryDemo { @TempDir static Path sharedTempDir ; @Test void writeItemsToFile () throws IOException { Path file = sharedTempDir . resolve ( "test.txt" ); new ListWriter ( file ). write ( "a" , "b" , "c" ); assertEquals ( singletonList ( "a,b,c" ), Files . readAllLines ( file )); } @Test void anotherTestThatUsesTheSameTempDir () { // use sharedTempDir } } 3. Migrating from JUnit 4
Although the JUnit Jupiter programming model and extension model will not support JUnit 4 features such as Rules and Runners natively, it is not expected that source code maintainers will need to update all of their existing tests, test extensions, and custom build test infrastructure to migrate to JUnit Jupiter.
Instead, JUnit provides a gentle migration path via a JUnit Vintage test engine which allows existing tests based on JUnit 3 and JUnit 4 to be executed using the JUnit Platform infrastructure. Since all classes and annotations specific to JUnit Jupiter reside under a new org.junit.jupiter base package, having both JUnit 4 and JUnit Jupiter in the classpath does not lead to any conflicts. It is therefore safe to maintain existing JUnit 4 tests alongside JUnit Jupiter tests. Furthermore, since the JUnit team will continue to provide maintenance and bug fix releases for the JUnit 4.x baseline, developers have plenty of time to migrate to JUnit Jupiter on their own schedule.
3.1. Running JUnit 4 Tests on the JUnit Platform
Just make sure that the junit-vintage-engine artifact is in your test runtime path. In that case JUnit 3 and JUnit 4 tests will automatically be picked up by the JUnit Platform launcher.
See the example projects in the junit5-samples repository to find out how this is done with Gradle and Maven.
3.1.1. Categories Support
For test classes or methods that are annotated with @Category, the JUnit Vintage test engine exposes the category's fully qualified class name as a tag of the corresponding test identifier. For example, if a test method is annotated with @Category(Example.class), it will be tagged with "com.acme.Example". Similar to the Categories runner in JUnit 4, this information can be used to filter the discovered tests before executing them (see Running Tests for details).
3.2. Migration Tips
The following are topics that you should be aware of when migrating existing JUnit 4 tests to JUnit Jupiter.
-
Annotations reside in the
org.junit.jupiter.apipackage. -
Assertions reside in
org.junit.jupiter.api.Assertions.-
Note that you may continue to use assertion methods from
org.junit.Assertor any other assertion library such as AssertJ, Hamcrest, Truth, etc.
-
-
Assumptions reside in
org.junit.jupiter.api.Assumptions.-
Note that JUnit Jupiter 5.4 and later versions support methods from JUnit 4's
org.junit.Assumeclass for assumptions. Specifically, JUnit Jupiter supports JUnit 4'sAssumptionViolatedExceptionto signal that a test should be aborted instead of marked as a failure.
-
-
@Beforeand@Afterno longer exist; use@BeforeEachand@AfterEachinstead. -
@BeforeClassand@AfterClassno longer exist; use@BeforeAlland@AfterAllinstead. -
@Ignoreno longer exists: use@Disabledor one of the other built-in execution conditions instead-
See also JUnit 4 @Ignore Support.
-
-
@Categoryno longer exists; use@Taginstead. -
@RunWithno longer exists; superseded by@ExtendWith. -
@Ruleand@ClassRuleno longer exist; superseded by@ExtendWithand@RegisterExtension-
See also Limited JUnit 4 Rule Support.
-
3.3. Limited JUnit 4 Rule Support
As stated above, JUnit Jupiter does not and will not support JUnit 4 rules natively. The JUnit team realizes, however, that many organizations, especially large ones, are likely to have large JUnit 4 code bases that make use of custom rules. To serve these organizations and enable a gradual migration path the JUnit team has decided to support a selection of JUnit 4 rules verbatim within JUnit Jupiter. This support is based on adapters and is limited to those rules that are semantically compatible to the JUnit Jupiter extension model, i.e. those that do not completely change the overall execution flow of the test.
The junit-jupiter-migrationsupport module from JUnit Jupiter currently supports the following three Rule types including subclasses of these types:
-
org.junit.rules.ExternalResource(includingorg.junit.rules.TemporaryFolder) -
org.junit.rules.Verifier(includingorg.junit.rules.ErrorCollector) -
org.junit.rules.ExpectedException
As in JUnit 4, Rule-annotated fields as well as methods are supported. By using these class-level extensions on a test class such Rule implementations in legacy code bases can be left unchanged including the JUnit 4 rule import statements.
This limited form of Rule support can be switched on by the class-level annotation @EnableRuleMigrationSupport. This annotation is a composed annotation which enables all rule migration support extensions: VerifierSupport, ExternalResourceSupport, and ExpectedExceptionSupport. You may alternatively choose to annotate your test class with @EnableJUnit4MigrationSupport which registers migration support for rules and JUnit 4's @Ignore annotation (see JUnit 4 @Ignore Support).
However, if you intend to develop a new extension for JUnit 5 please use the new extension model of JUnit Jupiter instead of the rule-based model of JUnit 4.
3.4. JUnit 4 @Ignore Support
In order to provide a smooth migration path from JUnit 4 to JUnit Jupiter, the junit-jupiter-migrationsupport module provides support for JUnit 4's @Ignore annotation analogous to Jupiter's @Disabled annotation.
To use @Ignore with JUnit Jupiter based tests, configure a test dependency on the junit-jupiter-migrationsupport module in your build and then annotate your test class with @ExtendWith(IgnoreCondition.class) or @EnableJUnit4MigrationSupport (which automatically registers the IgnoreCondition along with Limited JUnit 4 Rule Support). The IgnoreCondition is an ExecutionCondition that disables test classes or test methods that are annotated with @Ignore.
import org.junit.Ignore ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.migrationsupport.EnableJUnit4MigrationSupport ; // @ExtendWith(IgnoreCondition.class) @EnableJUnit4MigrationSupport class IgnoredTestsDemo { @Ignore @Test void testWillBeIgnored () { } @Test void testWillBeExecuted () { } } 4. Running Tests
4.1. IDE Support
4.1.1. IntelliJ IDEA
IntelliJ IDEA supports running tests on the JUnit Platform since version 2016.2. For details please see the post on the IntelliJ IDEA blog. Note, however, that it is recommended to use IDEA 2017.3 or newer since these newer versions of IDEA will download the following JARs automatically based on the API version used in the project: junit-platform-launcher, junit-jupiter-engine, and junit-vintage-engine.
| IntelliJ IDEA releases prior to IDEA 2017.3 bundle specific versions of JUnit 5. Thus, if you want to use a newer version of JUnit Jupiter, execution of tests within the IDE might fail due to version conflicts. In such cases, please follow the instructions below to use a newer version of JUnit 5 than the one bundled with IntelliJ IDEA. |
In order to use a different JUnit 5 version (e.g., 5.8.1), you may need to include the corresponding versions of the junit-platform-launcher, junit-jupiter-engine, and junit-vintage-engine JARs in the classpath.
Additional Gradle Dependencies
testImplementation ( platform ( "org.junit:junit-bom:5.8.1" )) // Only needed to run tests in a version of IntelliJ IDEA that bundles older versions testRuntimeOnly ( "org.junit.platform:junit-platform-launcher" ) testRuntimeOnly ( "org.junit.jupiter:junit-jupiter-engine" ) testRuntimeOnly ( "org.junit.vintage:junit-vintage-engine" ) Additional Maven Dependencies
<!-- ... --> <dependencies> <!-- Only needed to run tests in a version of IntelliJ IDEA that bundles older versions --> <dependency> <groupId>org.junit.platform</groupId> <artifactId>junit-platform-launcher</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId> <scope>test</scope> </dependency> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.junit</groupId> <artifactId>junit-bom</artifactId> <version>5.8.1</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> 4.1.2. Eclipse
Eclipse IDE offers support for the JUnit Platform since the Eclipse Oxygen.1a (4.7.1a) release.
4.1.3. NetBeans
4.1.4. Visual Studio Code
4.1.5. Other IDEs
If you are using an editor or IDE other than one of those listed in the previous sections, the JUnit team provides two alternative solutions to assist you in using JUnit 5. You can use the Console Launcher manually — for example, from the command line — or execute tests with a JUnit 4 based Runner if your IDE has built-in support for JUnit 4.
4.2. Build Support
4.2.1. Gradle
| The JUnit Platform Gradle Plugin has been discontinued The |
Starting with version 4.6, Gradle provides native support for executing tests on the JUnit Platform. To enable it, you just need to specify useJUnitPlatform() within a test task declaration in build.gradle:
test { useJUnitPlatform () } Filtering by tags, tag expressions, or engines is also supported:
test { useJUnitPlatform { includeTags ( "fast" , "smoke & feature-a" ) // excludeTags("slow", "ci") includeEngines ( "junit-jupiter" ) // excludeEngines("junit-vintage") } } Configuration Parameters
The standard Gradle test task currently does not provide a dedicated DSL to set JUnit Platform configuration parameters to influence test discovery and execution. However, you can provide configuration parameters within the build script via system properties (as shown below) or via the junit-platform.properties file.
test { // ... systemProperty ( "junit.jupiter.conditions.deactivate" , "*" ) systemProperty ( "junit.jupiter.extensions.autodetection.enabled" , true ) systemProperty ( "junit.jupiter.testinstance.lifecycle.default" , "per_class" ) // ... } Configuring Test Engines
In order to run any tests at all, a TestEngine implementation must be on the classpath.
To configure support for JUnit Jupiter based tests, configure a testImplementation dependency on the dependency-aggregating JUnit Jupiter artifact similar to the following.
dependencies { testImplementation ( "org.junit.jupiter:junit-jupiter:5.8.1" ) } The JUnit Platform can run JUnit 4 based tests as long as you configure a testImplementation dependency on JUnit 4 and a testRuntimeOnly dependency on the JUnit Vintage TestEngine implementation similar to the following.
dependencies { testImplementation ( "junit:junit:4.13.2" ) testRuntimeOnly ( "org.junit.vintage:junit-vintage-engine:5.8.1" ) } Configuring Logging (optional)
JUnit uses the Java Logging APIs in the java.util.logging package (a.k.a. JUL) to emit warnings and debug information. Please refer to the official documentation of LogManager for configuration options.
Alternatively, it's possible to redirect log messages to other logging frameworks such as Log4j or Logback. To use a logging framework that provides a custom implementation of LogManager, set the java.util.logging.manager system property to the fully qualified class name of the LogManager implementation to use. The example below demonstrates how to configure Log4j 2.x (see Log4j JDK Logging Adapter for details).
test { systemProperty ( "java.util.logging.manager" , "org.apache.logging.log4j.jul.LogManager" ) } Other logging frameworks provide different means to redirect messages logged using java.util.logging. For example, for Logback you can use the JUL to SLF4J Bridge by adding an additional dependency to the runtime classpath.
4.2.2. Maven
| The JUnit Platform Maven Surefire Provider has been discontinued The |
Starting with version 2.22.0, Maven Surefire and Maven Failsafe provide native support for executing tests on the JUnit Platform. The pom.xml file in the junit5-jupiter-starter-maven project demonstrates how to use the Maven Surefire plugin and can serve as a starting point for configuring your Maven build.
Configuring Test Engines
In order to have Maven Surefire or Maven Failsafe run any tests at all, at least one TestEngine implementation must be added to the test classpath.
To configure support for JUnit Jupiter based tests, configure test scoped dependencies on the JUnit Jupiter API and the JUnit Jupiter TestEngine implementation similar to the following.
<!-- ... --> <dependencies> <!-- ... --> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter</artifactId> <version>5.8.1</version> <scope>test</scope> </dependency> <!-- ... --> </dependencies> <build> <plugins> <plugin> <artifactId>maven-surefire-plugin</artifactId> <version>2.22.2</version> </plugin> <plugin> <artifactId>maven-failsafe-plugin</artifactId> <version>2.22.2</version> </plugin> </plugins> </build> <!-- ... --> Maven Surefire and Maven Failsafe can run JUnit 4 based tests alongside Jupiter tests as long as you configure test scoped dependencies on JUnit 4 and the JUnit Vintage TestEngine implementation similar to the following.
<!-- ... --> <dependencies> <!-- ... --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13.2</version> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId> <version>5.8.1</version> <scope>test</scope> </dependency> <!-- ... --> </dependencies> <!-- ... --> <build> <plugins> <plugin> <artifactId>maven-surefire-plugin</artifactId> <version>2.22.2</version> </plugin> <plugin> <artifactId>maven-failsafe-plugin</artifactId> <version>2.22.2</version> </plugin> </plugins> </build> <!-- ... --> Filtering by Test Class Names
The Maven Surefire Plugin will scan for test classes whose fully qualified names match the following patterns.
-
**/Test*.java -
**/*Test.java -
**/*Tests.java -
**/*TestCase.java
Moreover, it will exclude all nested classes (including static member classes) by default.
Note, however, that you can override this default behavior by configuring explicit include and exclude rules in your pom.xml file. For example, to keep Maven Surefire from excluding static member classes, you can override its exclude rules as follows.
Overriding exclude rules of Maven Surefire
<!-- ... --> <build> <plugins> <plugin> <artifactId>maven-surefire-plugin</artifactId> <version>2.22.2</version> <configuration> <excludes> <exclude/> </excludes> </configuration> </plugin> </plugins> </build> <!-- ... --> Filtering by Tags
You can filter tests by tags or tag expressions using the following configuration properties.
-
to include tags or tag expressions, use
groups. -
to exclude tags or tag expressions, use
excludedGroups.
<!-- ... --> <build> <plugins> <plugin> <artifactId>maven-surefire-plugin</artifactId> <version>2.22.2</version> <configuration> <groups>acceptance | !feature-a</groups> <excludedGroups>integration, regression</excludedGroups> </configuration> </plugin> </plugins> </build> <!-- ... --> Configuration Parameters
You can set JUnit Platform configuration parameters to influence test discovery and execution by declaring the configurationParameters property and providing key-value pairs using the Java Properties file syntax (as shown below) or via the junit-platform.properties file.
<!-- ... --> <build> <plugins> <plugin> <artifactId>maven-surefire-plugin</artifactId> <version>2.22.2</version> <configuration> <properties> <configurationParameters> junit.jupiter.conditions.deactivate = * junit.jupiter.extensions.autodetection.enabled = true junit.jupiter.testinstance.lifecycle.default = per_class </configurationParameters> </properties> </configuration> </plugin> </plugins> </build> <!-- ... --> 4.2.3. Ant
Starting with version 1.10.3 of Ant, a new junitlauncher task has been introduced to provide native support for launching tests on the JUnit Platform. The junitlauncher task is solely responsible for launching the JUnit Platform and passing it the selected collection of tests. The JUnit Platform then delegates to registered test engines to discover and execute the tests.
The junitlauncher task attempts to align as close as possible with native Ant constructs such as resource collections for allowing users to select the tests that they want executed by test engines. This gives the task a consistent and natural feel when compared to many other core Ant tasks.
The build.xml file in the junit5-jupiter-starter-ant project demonstrates how to use the task and can serve as a starting point.
Basic Usage
The following example demonstrates how to configure the junitlauncher task to select a single test class (i.e., org.myapp.test.MyFirstJUnit5Test).
<path id= "test.classpath" > <!-- The location where you have your compiled classes --> <pathelement location= "${build.classes.dir}" /> </path> <!-- ... --> <junitlauncher> <classpath refid= "test.classpath" /> <test name= "org.myapp.test.MyFirstJUnit5Test" /> </junitlauncher> The test element allows you to specify a single test class that you want to be selected and executed. The classpath element allows you to specify the classpath to be used to launch the JUnit Platform. This classpath will also be used to locate test classes that are part of the execution.
The following example demonstrates how to configure the junitlauncher task to select test classes from multiple locations.
<path id= "test.classpath" > <!-- The location where you have your compiled classes --> <pathelement location= "${build.classes.dir}" /> </path> <!-- ... --> <junitlauncher> <classpath refid= "test.classpath" /> <testclasses outputdir= "${output.dir}" > <fileset dir= "${build.classes.dir}" > <include name= "org/example/**/demo/**/" /> </fileset> <fileset dir= "${some.other.dir}" > <include name= "org/myapp/**/" /> </fileset> </testclasses> </junitlauncher> In the above example, the testclasses element allows you to select multiple test classes that reside in different locations.
For further details on usage and configuration options please refer to the official Ant documentation for the junitlauncher task.
4.3. Console Launcher
The ConsoleLauncher is a command-line Java application that lets you launch the JUnit Platform from the console. For example, it can be used to run JUnit Vintage and JUnit Jupiter tests and print test execution results to the console.
An executable junit-platform-console-standalone-1.8.1.jar with all dependencies included is published in the Maven Central repository under the junit-platform-console-standalone directory. You can run the standalone ConsoleLauncher as shown below.
java -jar junit-platform-console-standalone-1.8.1.jar <Options>
Here's an example of its output:
├─ JUnit Vintage │ └─ example.JUnit4Tests │ └─ standardJUnit4Test ✔ └─ JUnit Jupiter ├─ StandardTests │ ├─ succeedingTest() ✔ │ └─ skippedTest() ↷ for demonstration purposes └─ A special test case ├─ Custom test name containing spaces ✔ ├─ ╯°□°)╯ ✔ └─ 😱 ✔ Test run finished after 64 ms [ 5 containers found ] [ 0 containers skipped ] [ 5 containers started ] [ 0 containers aborted ] [ 5 containers successful ] [ 0 containers failed ] [ 6 tests found ] [ 1 tests skipped ] [ 5 tests started ] [ 0 tests aborted ] [ 5 tests successful ] [ 0 tests failed ]
| Exit Code TheConsoleLauncher exits with a status code of 1 if any containers or tests failed. If no tests are discovered and the --fail-if-no-tests command-line option is supplied, the ConsoleLauncher exits with a status code of 2. Otherwise the exit code is 0. |
4.3.1. Options
Usage: ConsoleLauncher [-h] [--disable-ansi-colors] [--disable-banner] [--fail-if-no-tests] [--scan-modules] [--scan-classpath[=PATH[;|: PATH...]]]... [--details=MODE] [--details-theme=THEME] [--reports-dir=DIR] [-c=CLASS]... [--config=KEY=VALUE]... [-cp=PATH [;|:PATH...]]... [-d=DIR]... [-e=ID]... [-E=ID]... [--exclude-package=PKG]... [-f=FILE]... [--include-package=PKG]... [-m=NAME]... [-n=PATTERN]... [-N=PATTERN]... [-o=NAME]... [-p=PKG]... [-r=RESOURCE]... [-t=TAG]... [-T=TAG]... [-u=URI]... Launches the JUnit Platform from the console. -h, --help Display help information. --disable-ansi-colors Disable ANSI colors in output (not supported by all terminals). --disable-banner Disable print out of the welcome message. --details=MODE Select an output details mode for when tests are executed. Use one of: none, summary, flat, tree, verbose. If 'none' is selected, then only the summary and test failures are shown. Default: tree. --details-theme=THEME Select an output details tree theme for when tests are executed. Use one of: ascii, unicode. Default: unicode. -cp, --classpath, --class-path=PATH[;|:PATH...] Provide additional classpath entries -- for example, for adding engines and their dependencies. This option can be repeated. --fail-if-no-tests Fail and return exit status code 2 if no tests are found. --reports-dir=DIR Enable report output into a specified local directory (will be created if it does not exist). --scan-modules EXPERIMENTAL: Scan all resolved modules for test discovery. -o, --select-module=NAME EXPERIMENTAL: Select single module for test discovery. This option can be repeated. --scan-classpath, --scan-class-path[=PATH[;|:PATH...]] Scan all directories on the classpath or explicit classpath roots. Without arguments, only directories on the system classpath as well as additional classpath entries supplied via -cp (directories and JAR files) are scanned. Explicit classpath roots that are not on the classpath will be silently ignored. This option can be repeated. -u, --select-uri=URI Select a URI for test discovery. This option can be repeated. -f, --select-file=FILE Select a file for test discovery. This option can be repeated. -d, --select-directory=DIR Select a directory for test discovery. This option can be repeated. -p, --select-package=PKG Select a package for test discovery. This option can be repeated. -c, --select-class=CLASS Select a class for test discovery. This option can be repeated. -m, --select-method=NAME Select a method for test discovery. This option can be repeated. -r, --select-resource=RESOURCE Select a classpath resource for test discovery. This option can be repeated. -n, --include-classname=PATTERN Provide a regular expression to include only classes whose fully qualified names match. To avoid loading classes unnecessarily, the default pattern only includes class names that begin with "Test" or end with "Test" or "Tests". When this option is repeated, all patterns will be combined using OR semantics. Default: [^(Test.*|.+[.$] Test.*|.*Tests?)$] -N, --exclude-classname=PATTERN Provide a regular expression to exclude those classes whose fully qualified names match. When this option is repeated, all patterns will be combined using OR semantics. --include-package=PKG Provide a package to be included in the test run. This option can be repeated. --exclude-package=PKG Provide a package to be excluded from the test run. This option can be repeated. -t, --include-tag=TAG Provide a tag or tag expression to include only tests whose tags match. When this option is repeated, all patterns will be combined using OR semantics. -T, --exclude-tag=TAG Provide a tag or tag expression to exclude those tests whose tags match. When this option is repeated, all patterns will be combined using OR semantics. -e, --include-engine=ID Provide the ID of an engine to be included in the test run. This option can be repeated. -E, --exclude-engine=ID Provide the ID of an engine to be excluded from the test run. This option can be repeated. --config=KEY=VALUE Set a configuration parameter for test discovery and execution. This option can be repeated.
4.3.2. Argument Files (@-files)
On some platforms you may run into system limitations on the length of a command line when creating a command line with lots of options or with long arguments.
Since version 1.3, the ConsoleLauncher supports argument files, also known as @-files. Argument files are files that themselves contain arguments to be passed to the command. When the underlying picocli command line parser encounters an argument beginning with the character @, it expands the contents of that file into the argument list.
The arguments within a file can be separated by spaces or newlines. If an argument contains embedded whitespace, the whole argument should be wrapped in double or single quotes — for example, "-f=My Files/Stuff.java".
If the argument file does not exist or cannot be read, the argument will be treated literally and will not be removed. This will likely result in an "unmatched argument" error message. You can troubleshoot such errors by executing the command with the picocli.trace system property set to DEBUG.
Multiple @-files may be specified on the command line. The specified path may be relative to the current directory or absolute.
You can pass a real parameter with an initial @ character by escaping it with an additional @ symbol. For example, @@somearg will become @somearg and will not be subject to expansion.
4.4. Using JUnit 4 to run the JUnit Platform
| The The In recent years, all mainstream build tools and IDEs provide built-in support for running tests directly on the JUnit Platform. In addition, the introduction of The If you are using the |
The JUnitPlatform runner is a JUnit 4 based Runner which enables you to run any test whose programming model is supported on the JUnit Platform in a JUnit 4 environment — for example, a JUnit Jupiter test class.
Annotating a class with @RunWith(JUnitPlatform.class) allows it to be run with IDEs and build systems that support JUnit 4 but do not yet support the JUnit Platform directly.
| Since the JUnit Platform has features that JUnit 4 does not have, the runner is only able to support a subset of the JUnit Platform functionality, especially with regard to reporting (see Display Names vs. Technical Names). |
4.4.1. Setup
You need the following artifacts and their dependencies on the classpath. See Dependency Metadata for details regarding group IDs, artifact IDs, and versions.
Explicit Dependencies
-
junit-platform-runnerin test scope: location of theJUnitPlatformrunner -
junit-4.13.2.jarin test scope: to run tests using JUnit 4 -
junit-jupiter-apiin test scope: API for writing tests using JUnit Jupiter, including@Test, etc. -
junit-jupiter-enginein test runtime scope: implementation of theTestEngineAPI for JUnit Jupiter
Transitive Dependencies
-
junit-platform-suite-apiin test scope -
junit-platform-suite-commonsin test scope -
junit-platform-launcherin test scope -
junit-platform-enginein test scope -
junit-platform-commonsin test scope -
opentest4jin test scope
4.4.2. Display Names vs. Technical Names
To define a custom display name for the class run via @RunWith(JUnitPlatform.class) annotate the class with @SuiteDisplayName and provide a custom value.
By default, display names will be used for test artifacts; however, when the JUnitPlatform runner is used to execute tests with a build tool such as Gradle or Maven, the generated test report often needs to include the technical names of test artifacts — for example, fully qualified class names — instead of shorter display names like the simple name of a test class or a custom display name containing special characters. To enable technical names for reporting purposes, declare the @UseTechnicalNames annotation alongside @RunWith(JUnitPlatform.class).
Note that the presence of @UseTechnicalNames overrides any custom display name configured via @SuiteDisplayName.
4.4.3. Single Test Class
One way to use the JUnitPlatform runner is to annotate a test class with @RunWith(JUnitPlatform.class) directly. Please note that the test methods in the following example are annotated with org.junit.jupiter.api.Test (JUnit Jupiter), not org.junit.Test (JUnit 4). Moreover, in this case the test class must be public; otherwise, some IDEs and build tools might not recognize it as a JUnit 4 test class.
import static org . junit . jupiter . api . Assertions . fail ; import org.junit.jupiter.api.Test ; import org.junit.runner.RunWith ; @RunWith ( org . junit . platform . runner . JUnitPlatform . class ) public class JUnitPlatformClassDemo { @Test void succeedingTest () { /* no-op */ } @Test void failingTest () { fail ( "Failing for failing's sake." ); } } 4.4.4. Test Suite
If you have multiple test classes you can create a test suite as can be seen in the following example.
import org.junit.platform.suite.api.SelectPackages ; import org.junit.platform.suite.api.SuiteDisplayName ; import org.junit.runner.RunWith ; @RunWith ( org . junit . platform . runner . JUnitPlatform . class ) @SuiteDisplayName ( "JUnit Platform Suite Demo" ) @SelectPackages ( "example" ) public class JUnitPlatformSuiteDemo { } The JUnitPlatformSuiteDemo will discover and run all tests in the example package and its subpackages. By default, it will only include test classes whose names either begin with Test or end with Test or Tests.
| Additional Configuration Options There are more configuration options for discovering and filtering tests than just@SelectPackages. Please consult the Javadoc of the org.junit.platform.suite.api package for further details. |
Test classes and suites annotated with @RunWith(JUnitPlatform.class) cannot be executed directly on the JUnit Platform (or as a "JUnit 5" test as documented in some IDEs). Such classes and suites can only be executed using JUnit 4 infrastructure. |
4.5. Configuration Parameters
In addition to instructing the platform which test classes and test engines to include, which packages to scan, etc., it is sometimes necessary to provide additional custom configuration parameters that are specific to a particular test engine, listener, or registered extension. For example, the JUnit Jupiter TestEngine supports configuration parameters for the following use cases.
-
Changing the Default Test Instance Lifecycle
-
Enabling Automatic Extension Detection
-
Deactivating Conditions
-
Setting the Default Display Name Generator
Configuration Parameters are text-based key-value pairs that can be supplied to test engines running on the JUnit Platform via one of the following mechanisms.
-
The
configurationParameter()andconfigurationParameters()methods in theLauncherDiscoveryRequestBuilderwhich is used to build a request supplied to theLauncherAPI. When running tests via one of the tools provided by the JUnit Platform you can specify configuration parameters as follows:-
Console Launcher: use the
--configcommand-line option. -
Gradle: use the
systemPropertyorsystemPropertiesDSL. -
Maven Surefire provider: use the
configurationParametersproperty.
-
-
JVM system properties.
-
The JUnit Platform configuration file: a file named
junit-platform.propertiesin the root of the class path that follows the syntax rules for a JavaPropertiesfile.
Configuration parameters are looked up in the exact order defined above. Consequently, configuration parameters supplied directly to the Launcher take precedence over those supplied via system properties and the configuration file. Similarly, configuration parameters supplied via system properties take precedence over those supplied via the configuration file. |
4.5.1. Pattern Matching Syntax
This section describes the pattern matching syntax that is applied to the configuration parameters used for the following features.
-
Deactivating Conditions
-
Deactivating a TestExecutionListener
If the value for the given configuration parameter consists solely of an asterisk (*), the pattern will match against all candidate classes. Otherwise, the value will be treated as a comma-separated list of patterns where each pattern will be matched against the fully qualified class name (FQCN) of each candidate class. Any dot (.) in a pattern will match against a dot (.) or a dollar sign ($) in a FQCN. Any asterisk (*) will match against one or more characters in a FQCN. All other characters in a pattern will be matched one-to-one against a FQCN.
Examples:
-
*: matches all candidate classes. -
org.junit.*: matches all candidate classes under theorg.junitbase package and any of its subpackages. -
*.MyCustomImpl: matches every candidate class whose simple class name is exactlyMyCustomImpl. -
*System*: matches every candidate class whose FQCN containsSystem. -
*System*+, +*Unit*: matches every candidate class whose FQCN containsSystemorUnit. -
org.example.MyCustomImpl: matches the candidate class whose FQCN is exactlyorg.example.MyCustomImpl. -
org.example.MyCustomImpl, org.example.TheirCustomImpl: matches candidate classes whose FQCN is exactlyorg.example.MyCustomImplororg.example.TheirCustomImpl.
4.6. Tags
Tags are a JUnit Platform concept for marking and filtering tests. The programming model for adding tags to containers and tests is defined by the testing framework. For example, in JUnit Jupiter based tests, the @Tag annotation (see Tagging and Filtering) should be used. For JUnit 4 based tests, the Vintage engine maps @Category annotations to tags (see Categories Support). Other testing frameworks may define their own annotation or other means for users to specify tags.
4.6.1. Syntax Rules for Tags
Regardless how a tag is specified, the JUnit Platform enforces the following rules:
-
A tag must not be
nullor blank. -
A trimmed tag must not contain whitespace.
-
A trimmed tag must not contain ISO control characters.
-
A trimmed tag must not contain any of the following reserved characters.
-
,: comma -
(: left parenthesis -
): right parenthesis -
&: ampersand -
|: vertical bar -
!: exclamation point
-
| In the above context, "trimmed" means that leading and trailing whitespace characters have been removed. |
4.6.2. Tag Expressions
Tag expressions are boolean expressions with the operators !, & and |. In addition, ( and ) can be used to adjust for operator precedence.
Two special expressions are supported, any() and none(), which select all tests with any tags at all, and all tests without any tags, respectively. These special expressions may be combined with other expressions just like normal tags.
| Operator | Meaning | Associativity |
|---|---|---|
| | not | right |
| | and | left |
| | or | left |
If you are tagging your tests across multiple dimensions, tag expressions help you to select which tests to execute. When tagging by test type (e.g., micro, integration, end-to-end) and feature (e.g., product, catalog, shipping), the following tag expressions can be useful.
| Tag Expression | Selection |
|---|---|
| product | all tests for product |
| catalog | shipping | all tests for catalog plus all tests for shipping |
| catalog & shipping | all tests for the intersection between catalog and shipping |
| product & !end-to-end | all tests for product, but not the end-to-end tests |
| (micro | integration) & (product | shipping) | all micro or integration tests for product or shipping |
4.7. Capturing Standard Output/Error
Since version 1.3, the JUnit Platform provides opt-in support for capturing output printed to System.out and System.err. To enable it, set the junit.platform.output.capture.stdout and/or junit.platform.output.capture.stderr configuration parameter to true. In addition, you may configure the maximum number of buffered bytes to be used per executed test or container using junit.platform.output.capture.maxBuffer.
If enabled, the JUnit Platform captures the corresponding output and publishes it as a report entry using the stdout or stderr keys to all registered TestExecutionListener instances immediately before reporting the test or container as finished.
Please note that the captured output will only contain output emitted by the thread that was used to execute a container or test. Any output by other threads will be omitted because particularly when executing tests in parallel it would be impossible to attribute it to a specific test or container.
4.8. Using Listeners
The JUnit Platform provides the following listener APIs that allow JUnit, third parties, and custom user code to react to events fired at various points during the discovery and execution of a TestPlan.
-
LauncherSessionListener: receives events when aLauncherSessionis opened and closed. -
LauncherDiscoveryListener: receives events that occur during test discovery. -
TestExecutionListener: receives events that occur during test execution.
The LauncherSessionListener API is typically implemented by build tools or IDEs and registered automatically for you in order to support some feature of the build tool or IDE.
The LauncherDiscoveryListener and TestExecutionListener APIs are often implemented in order to produce some form of report or to display a graphical representation of the test plan in an IDE. Such listeners may be implemented and automatically registered by a build tool or IDE, or they may be included in a third-party library – potentially registered for you automatically. You can also implement and register your own listeners.
For details on registering and configuring listeners, see the following sections of this guide.
-
Registering a LauncherSessionListener
-
Registering a LauncherDiscoveryListener
-
Registering a TestExecutionListener
-
Configuring a TestExecutionListener
-
Deactivating a TestExecutionListener
The JUnit Platform provides the following listeners which you may wish to use with your test suite.
- Flight Recorder Support
-
FlightRecordingExecutionListenerandFlightRecordingDiscoveryListenerthat generate Java Flight Recorder events during test discovery and execution. -
LegacyXmlReportGeneratingListener -
TestExecutionListenerthat generates XML reports compatible with the de facto standard for JUnit 4 based test reports. See JUnit Platform Reporting for details. -
LoggingListener -
TestExecutionListenerfor logging informational messages for all events via aBiConsumerthat consumesThrowableandSupplier<String>. -
SummaryGeneratingListener -
TestExecutionListenerthat generates a summary of the test execution which can be printed via aPrintWriter. -
UniqueIdTrackingListener -
TestExecutionListenerthat that tracks the unique IDs of all tests that were skipped or executed during the execution of theTestPlanand generates a file containing the unique IDs once execution of theTestPlanhas finished.
4.8.1. Flight Recorder Support
Since version 1.7, the JUnit Platform provides opt-in support for generating Flight Recorder events. JEP 328 describes the Java Flight Recorder (JFR) as:
| Flight Recorder records events originating from applications, the JVM and the OS. Events are stored in a single file that can be attached to bug reports and examined by support engineers, allowing after-the-fact analysis of issues in the period leading up to a problem. |
In order to record Flight Recorder events generated while running tests, you need to:
-
Ensure that you are using either Java 8 Update 262 or higher or Java 11 or later.
-
Provide the
org.junit.platform.jfrmodule (junit-platform-jfr-1.8.1.jar) on the class-path or module-path at test runtime. -
Start flight recording when launching a test run. Flight Recorder can be started via java command line option:
-XX:StartFlightRecording:filename=...
Please consult the manual of your build tool for the appropriate commands.
To analyze the recorded events, use the jfr command line tool shipped with recent JDKs or open the recording file with JDK Mission Control.
| Flight Recorder support is currently an experimental feature. You're invited to give it a try and provide feedback to the JUnit team so they can improve and eventually promote this feature. |
5. Extension Model
5.1. Overview
In contrast to the competing Runner, TestRule, and MethodRule extension points in JUnit 4, the JUnit Jupiter extension model consists of a single, coherent concept: the Extension API. Note, however, that Extension itself is just a marker interface.
5.2. Registering Extensions
Extensions can be registered declaratively via @ExtendWith, programmatically via @RegisterExtension, or automatically via Java's ServiceLoader mechanism.
5.2.1. Declarative Extension Registration
Developers can register one or more extensions declaratively by annotating a test interface, test class, test method, or custom composed annotation with @ExtendWith(…) and supplying class references for the extensions to register. As of JUnit Jupiter 5.8, @ExtendWith may also be declared on fields or on parameters in test class constructors, in test methods, and in @BeforeAll, @AfterAll, @BeforeEach, and @AfterEach lifecycle methods.
For example, to register a WebServerExtension for a particular test method, you would annotate the test method as follows. We assume the WebServerExtension starts a local web server and injects the server's URL into parameters annotated with @WebServerUrl.
@Test @ExtendWith ( WebServerExtension . class ) void getProductList ( @WebServerUrl String serverUrl ) { WebClient webClient = new WebClient (); // Use WebClient to connect to web server using serverUrl and verify response assertEquals ( 200 , webClient . get ( serverUrl + "/products" ). getResponseStatus ()); } To register the WebServerExtension for all tests in a particular class and its subclasses, you would annotate the test class as follows.
@ExtendWith ( WebServerExtension . class ) class MyTests { // ... } Multiple extensions can be registered together like this:
@ExtendWith ({ DatabaseExtension . class , WebServerExtension . class }) class MyFirstTests { // ... } As an alternative, multiple extensions can be registered separately like this:
@ExtendWith ( DatabaseExtension . class ) @ExtendWith ( WebServerExtension . class ) class MySecondTests { // ... } | Extension Registration Order Extensions registered declaratively via |
If you wish to combine multiple extensions in a reusable way, you can define a custom composed annotation and use @ExtendWith as a meta-annotation as in the following code listing. Then @DatabaseAndWebServerExtension can be used in place of @ExtendWith({ DatabaseExtension.class, WebServerExtension.class }).
@Target ({ ElementType . TYPE , ElementType . METHOD }) @Retention ( RetentionPolicy . RUNTIME ) @ExtendWith ({ DatabaseExtension . class , WebServerExtension . class }) public @interface DatabaseAndWebServerExtension { } The above examples demonstrate how @ExtendWith can be applied at the class level or at the method level; however, for certain use cases it makes sense for an extension to be registered declaratively at the field or parameter level. Consider a RandomNumberExtension that generates random numbers that can be injected into a field or via a parameter in a constructor, test method, or lifecycle method. If the extension provides a @Random annotation that is meta-annotated with @ExtendWith(RandomNumberExtension.class) (see listing below), the extension can be used transparently as in the following RandomNumberDemo example.
@Target ({ ElementType . FIELD , ElementType . PARAMETER }) @Retention ( RetentionPolicy . RUNTIME ) @ExtendWith ( RandomNumberExtension . class ) public @interface Random { } class RandomNumberDemo { // use random number field in test methods and @BeforeEach // or @AfterEach lifecycle methods @Random private int randomNumber1 ; RandomNumberDemo ( @Random int randomNumber2 ) { // use random number in constructor } @BeforeEach void beforeEach ( @Random int randomNumber3 ) { // use random number in @BeforeEach method } @Test void test ( @Random int randomNumber4 ) { // use random number in test method } } | Extension Registration Order for Extensions registered declaratively via |
@ExtendWith fields may be either static or non-static. The documentation on Static Fields and Instance Fields for @RegisterExtension fields also applies to @ExtendWith fields. |
5.2.2. Programmatic Extension Registration
Developers can register extensions programmatically by annotating fields in test classes with @RegisterExtension.
When an extension is registered declaratively via @ExtendWith, it can typically only be configured via annotations. In contrast, when an extension is registered via @RegisterExtension, it can be configured programmatically — for example, in order to pass arguments to the extension's constructor, a static factory method, or a builder API.
| Extension Registration Order By default, extensions registered programmatically via Any |
@RegisterExtension fields must not be null (at evaluation time) but may be either static or non-static. |
Static Fields
If a @RegisterExtension field is static, the extension will be registered after extensions that are registered at the class level via @ExtendWith. Such static extensions are not limited in which extension APIs they can implement. Extensions registered via static fields may therefore implement class-level and instance-level extension APIs such as BeforeAllCallback, AfterAllCallback, TestInstancePostProcessor, and TestInstancePreDestroyCallback as well as method-level extension APIs such as BeforeEachCallback, etc.
In the following example, the server field in the test class is initialized programmatically by using a builder pattern supported by the WebServerExtension. The configured WebServerExtension will be automatically registered as an extension at the class level — for example, in order to start the server before all tests in the class and then stop the server after all tests in the class have completed. In addition, static lifecycle methods annotated with @BeforeAll or @AfterAll as well as @BeforeEach, @AfterEach, and @Test methods can access the instance of the extension via the server field if necessary.
Registering an extension via a static field in Java
class WebServerDemo { @RegisterExtension static WebServerExtension server = WebServerExtension . builder () . enableSecurity ( false ) . build (); @Test void getProductList () { WebClient webClient = new WebClient (); String serverUrl = server . getServerUrl (); // Use WebClient to connect to web server using serverUrl and verify response assertEquals ( 200 , webClient . get ( serverUrl + "/products" ). getResponseStatus ()); } } Static Fields in Kotlin
The Kotlin programming language does not have the concept of a static field. However, the compiler can be instructed to generate a private static field using the @JvmStatic annotation in Kotlin. If you want the Kotlin compiler to generate a public static field, you can use the @JvmField annotation instead.
The following example is a version of the WebServerDemo from the previous section that has been ported to Kotlin.
Registering an extension via a static field in Kotlin
class KotlinWebServerDemo { companion object { @JvmStatic @RegisterExtension val server = WebServerExtension . builder () . enableSecurity ( false ) . build () } @Test fun getProductList () { // Use WebClient to connect to web server using serverUrl and verify response val webClient = WebClient () val serverUrl = server . serverUrl assertEquals ( 200 , webClient . get ( "$serverUrl/products" ). responseStatus ) } } Instance Fields
If a @RegisterExtension field is non-static (i.e., an instance field), the extension will be registered after the test class has been instantiated and after each registered TestInstancePostProcessor has been given a chance to post-process the test instance (potentially injecting the instance of the extension to be used into the annotated field). Thus, if such an instance extension implements class-level or instance-level extension APIs such as BeforeAllCallback, AfterAllCallback, or TestInstancePostProcessor, those APIs will not be honored. By default, an instance extension will be registered after extensions that are registered at the method level via @ExtendWith; however, if the test class is configured with @TestInstance(Lifecycle.PER_CLASS) semantics, an instance extension will be registered before extensions that are registered at the method level via @ExtendWith.
In the following example, the docs field in the test class is initialized programmatically by invoking a custom lookUpDocsDir() method and supplying the result to the static forPath() factory method in the DocumentationExtension. The configured DocumentationExtension will be automatically registered as an extension at the method level. In addition, @BeforeEach, @AfterEach, and @Test methods can access the instance of the extension via the docs field if necessary.
An extension registered via an instance field
class DocumentationDemo { static Path lookUpDocsDir () { // return path to docs dir } @RegisterExtension DocumentationExtension docs = DocumentationExtension . forPath ( lookUpDocsDir ()); @Test void generateDocumentation () { // use this.docs ... } } 5.2.3. Automatic Extension Registration
In addition to declarative extension registration and programmatic extension registration support using annotations, JUnit Jupiter also supports global extension registration via Java's ServiceLoader mechanism, allowing third-party extensions to be auto-detected and automatically registered based on what is available in the classpath.
Specifically, a custom extension can be registered by supplying its fully qualified class name in a file named org.junit.jupiter.api.extension.Extension within the /META-INF/services folder in its enclosing JAR file.
Enabling Automatic Extension Detection
Auto-detection is an advanced feature and is therefore not enabled by default. To enable it, set the junit.jupiter.extensions.autodetection.enabled configuration parameter to true. This can be supplied as a JVM system property, as a configuration parameter in the LauncherDiscoveryRequest that is passed to the Launcher, or via the JUnit Platform configuration file (see Configuration Parameters for details).
For example, to enable auto-detection of extensions, you can start your JVM with the following system property.
-Djunit.jupiter.extensions.autodetection.enabled=true
When auto-detection is enabled, extensions discovered via the ServiceLoader mechanism will be added to the extension registry after JUnit Jupiter's global extensions (e.g., support for TestInfo, TestReporter, etc.).
5.2.4. Extension Inheritance
Registered extensions are inherited within test class hierarchies with top-down semantics. Similarly, extensions registered at the class-level are inherited at the method-level. Furthermore, a specific extension implementation can only be registered once for a given extension context and its parent contexts. Consequently, any attempt to register a duplicate extension implementation will be ignored.
5.3. Conditional Test Execution
ExecutionCondition defines the Extension API for programmatic, conditional test execution.
An ExecutionCondition is evaluated for each container (e.g., a test class) to determine if all the tests it contains should be executed based on the supplied ExtensionContext. Similarly, an ExecutionCondition is evaluated for each test to determine if a given test method should be executed based on the supplied ExtensionContext.
When multiple ExecutionCondition extensions are registered, a container or test is disabled as soon as one of the conditions returns disabled. Thus, there is no guarantee that a condition is evaluated because another extension might have already caused a container or test to be disabled. In other words, the evaluation works like the short-circuiting boolean OR operator.
5.3.1. Deactivating Conditions
Sometimes it can be useful to run a test suite without certain conditions being active. For example, you may wish to run tests even if they are annotated with @Disabled in order to see if they are still broken. To do this, provide a pattern for the junit.jupiter.conditions.deactivate configuration parameter to specify which conditions should be deactivated (i.e., not evaluated) for the current test run. The pattern can be supplied as a JVM system property, as a configuration parameter in the LauncherDiscoveryRequest that is passed to the Launcher, or via the JUnit Platform configuration file (see Configuration Parameters for details).
For example, to deactivate JUnit's @Disabled condition, you can start your JVM with the following system property.
-Djunit.jupiter.conditions.deactivate=org.junit.*DisabledCondition
Pattern Matching Syntax
Refer to Pattern Matching Syntax for details.
5.4. Test Instance Factories
TestInstanceFactory defines the API for Extensions that wish to create test class instances.
Common use cases include acquiring the test instance from a dependency injection framework or invoking a static factory method to create the test class instance.
If no TestInstanceFactory is registered, the framework will invoke the sole constructor for the test class to instantiate it, potentially resolving constructor arguments via registered ParameterResolver extensions.
Extensions that implement TestInstanceFactory can be registered on test interfaces, top-level test classes, or @Nested test classes.
| Registering multiple extensions that implement |
5.5. Test Instance Post-processing
Common use cases include injecting dependencies into the test instance, invoking custom initialization methods on the test instance, etc.
5.6. Test Instance Pre-destroy Callback
TestInstancePreDestroyCallback defines the API for Extensions that wish to process test instances after they have been used in tests and before they are destroyed.
Common use cases include cleaning dependencies that have been injected into the test instance, invoking custom de-initialization methods on the test instance, etc.
5.7. Parameter Resolution
ParameterResolver defines the Extension API for dynamically resolving parameters at runtime.
If a test class constructor, test method, or lifecycle method (see Test Classes and Methods) declares a parameter, the parameter must be resolved at runtime by a ParameterResolver. A ParameterResolver can either be built-in (see TestInfoParameterResolver) or registered by the user. Generally speaking, parameters may be resolved by name, type, annotation, or any combination thereof.
If you wish to implement a custom ParameterResolver that resolves parameters based solely on the type of the parameter, you may find it convenient to extend the TypeBasedParameterResolver which serves as a generic adapter for such use cases.
| Due to a bug in the byte code generated by The
|
5.8. Test Result Processing
TestWatcher defines the API for extensions that wish to process the results of test method executions. Specifically, a TestWatcher will be invoked with contextual information for the following events.
-
testDisabled: invoked after a disabled test method has been skipped -
testSuccessful: invoked after a test method has completed successfully -
testAborted: invoked after a test method has been aborted -
testFailed: invoked after a test method has failed
In contrast to the definition of "test method" presented in Test Classes and Methods, in this context test method refers to any @Test method or @TestTemplate method (for example, a @RepeatedTest or @ParameterizedTest). |
Extensions implementing this interface can be registered at the method level or at the class level. In the latter case they will be invoked for any contained test method including those in @Nested classes.
| Any instances of |
5.9. Test Lifecycle Callbacks
The following interfaces define the APIs for extending tests at various points in the test execution lifecycle. Consult the following sections for examples and the Javadoc for each of these interfaces in the org.junit.jupiter.api.extension package for further details.
-
BeforeAllCallback-
BeforeEachCallback-
BeforeTestExecutionCallback -
AfterTestExecutionCallback
-
-
AfterEachCallback
-
-
AfterAllCallback
| Implementing Multiple Extension APIs Extension developers may choose to implement any number of these interfaces within a single extension. Consult the source code of theSpringExtension for a concrete example. |
5.9.1. Before and After Test Execution Callbacks
BeforeTestExecutionCallback and AfterTestExecutionCallback define the APIs for Extensions that wish to add behavior that will be executed immediately before and immediately after a test method is executed, respectively. As such, these callbacks are well suited for timing, tracing, and similar use cases. If you need to implement callbacks that are invoked around @BeforeEach and @AfterEach methods, implement BeforeEachCallback and AfterEachCallback instead.
The following example shows how to use these callbacks to calculate and log the execution time of a test method. TimingExtension implements both BeforeTestExecutionCallback and AfterTestExecutionCallback in order to time and log the test execution.
An extension that times and logs the execution of test methods
import java.lang.reflect.Method ; import java.util.logging.Logger ; import org.junit.jupiter.api.extension.AfterTestExecutionCallback ; import org.junit.jupiter.api.extension.BeforeTestExecutionCallback ; import org.junit.jupiter.api.extension.ExtensionContext ; import org.junit.jupiter.api.extension.ExtensionContext.Namespace ; import org.junit.jupiter.api.extension.ExtensionContext.Store ; public class TimingExtension implements BeforeTestExecutionCallback , AfterTestExecutionCallback { private static final Logger logger = Logger . getLogger ( TimingExtension . class . getName ()); private static final String START_TIME = "start time" ; @Override public void beforeTestExecution ( ExtensionContext context ) throws Exception { getStore ( context ). put ( START_TIME , System . currentTimeMillis ()); } @Override public void afterTestExecution ( ExtensionContext context ) throws Exception { Method testMethod = context . getRequiredTestMethod (); long startTime = getStore ( context ). remove ( START_TIME , long . class ); long duration = System . currentTimeMillis () - startTime ; logger . info (() -> String . format ( "Method [%s] took %s ms." , testMethod . getName (), duration )); } private Store getStore ( ExtensionContext context ) { return context . getStore ( Namespace . create ( getClass (), context . getRequiredTestMethod ())); } } Since the TimingExtensionTests class registers the TimingExtension via @ExtendWith, its tests will have this timing applied when they execute.
A test class that uses the example TimingExtension
@ExtendWith ( TimingExtension . class ) class TimingExtensionTests { @Test void sleep20ms () throws Exception { Thread . sleep ( 20 ); } @Test void sleep50ms () throws Exception { Thread . sleep ( 50 ); } } The following is an example of the logging produced when TimingExtensionTests is run.
INFO: Method [sleep20ms] took 24 ms. INFO: Method [sleep50ms] took 53 ms.
5.10. Exception Handling
Exceptions thrown during the test execution may be intercepted and handled accordingly before propagating further, so that certain actions like error logging or resource releasing may be defined in specialized Extensions. JUnit Jupiter offers API for Extensions that wish to handle exceptions thrown during @Test methods via TestExecutionExceptionHandler and for those thrown during one of test lifecycle methods (@BeforeAll, @BeforeEach, @AfterEach and @AfterAll) via LifecycleMethodExecutionExceptionHandler.
The following example shows an extension which will swallow all instances of IOException but rethrow any other type of exception.
An exception handling extension that filters IOExceptions in test execution
public class IgnoreIOExceptionExtension implements TestExecutionExceptionHandler { @Override public void handleTestExecutionException ( ExtensionContext context , Throwable throwable ) throws Throwable { if ( throwable instanceof IOException ) { return ; } throw throwable ; } } Another example shows how to record the state of an application under test exactly at the point of unexpected exception being thrown during setup and cleanup. Note that unlike relying on lifecycle callbacks, which may or may not be executed depending on the test status, this solution guarantees execution immediately after failing @BeforeAll, @BeforeEach, @AfterEach or @AfterAll.
An exception handling extension that records application state on error
class RecordStateOnErrorExtension implements LifecycleMethodExecutionExceptionHandler { @Override public void handleBeforeAllMethodExecutionException ( ExtensionContext context , Throwable ex ) throws Throwable { memoryDumpForFurtherInvestigation ( "Failure recorded during class setup" ); throw ex ; } @Override public void handleBeforeEachMethodExecutionException ( ExtensionContext context , Throwable ex ) throws Throwable { memoryDumpForFurtherInvestigation ( "Failure recorded during test setup" ); throw ex ; } @Override public void handleAfterEachMethodExecutionException ( ExtensionContext context , Throwable ex ) throws Throwable { memoryDumpForFurtherInvestigation ( "Failure recorded during test cleanup" ); throw ex ; } @Override public void handleAfterAllMethodExecutionException ( ExtensionContext context , Throwable ex ) throws Throwable { memoryDumpForFurtherInvestigation ( "Failure recorded during class cleanup" ); throw ex ; } } Multiple execution exception handlers may be invoked for the same lifecycle method in order of declaration. If one of the handlers swallows the handled exception, subsequent ones will not be executed, and no failure will be propagated to JUnit engine, as if the exception was never thrown. Handlers may also choose to rethrow the exception or throw a different one, potentially wrapping the original.
Extensions implementing LifecycleMethodExecutionExceptionHandler that wish to handle exceptions thrown during @BeforeAll or @AfterAll need to be registered on a class level, while handlers for BeforeEach and AfterEach may be also registered for individual test methods.
Registering multiple exception handling extensions
// Register handlers for @Test, @BeforeEach, @AfterEach as well as @BeforeAll and @AfterAll @ExtendWith ( ThirdExecutedHandler . class ) class MultipleHandlersTestCase { // Register handlers for @Test, @BeforeEach, @AfterEach only @ExtendWith ( SecondExecutedHandler . class ) @ExtendWith ( FirstExecutedHandler . class ) @Test void testMethod () { } } 5.11. Intercepting Invocations
InvocationInterceptor defines the API for Extensions that wish to intercept calls to test code.
The following example shows an extension that executes all test methods in Swing's Event Dispatch Thread.
An extension that executes tests in a user-defined thread
public class SwingEdtInterceptor implements InvocationInterceptor { @Override public void interceptTestMethod ( Invocation < Void > invocation , ReflectiveInvocationContext < Method > invocationContext , ExtensionContext extensionContext ) throws Throwable { AtomicReference < Throwable > throwable = new AtomicReference <>(); SwingUtilities . invokeAndWait (() -> { try { invocation . proceed (); } catch ( Throwable t ) { throwable . set ( t ); } }); Throwable t = throwable . get (); if ( t != null ) { throw t ; } } } 5.12. Providing Invocation Contexts for Test Templates
A @TestTemplate method can only be executed when at least one TestTemplateInvocationContextProvider is registered. Each such provider is responsible for providing a Stream of TestTemplateInvocationContext instances. Each context may specify a custom display name and a list of additional extensions that will only be used for the next invocation of the @TestTemplate method.
A test template with accompanying extension
final List < String > fruits = Arrays . asList ( "apple" , "banana" , "lemon" ); @TestTemplate @ExtendWith ( MyTestTemplateInvocationContextProvider . class ) void testTemplate ( String fruit ) { assertTrue ( fruits . contains ( fruit )); } public class MyTestTemplateInvocationContextProvider implements TestTemplateInvocationContextProvider { @Override public boolean supportsTestTemplate ( ExtensionContext context ) { return true ; } @Override public Stream < TestTemplateInvocationContext > provideTestTemplateInvocationContexts ( ExtensionContext context ) { return Stream . of ( invocationContext ( "apple" ), invocationContext ( "banana" )); } private TestTemplateInvocationContext invocationContext ( String parameter ) { return new TestTemplateInvocationContext () { @Override public String getDisplayName ( int invocationIndex ) { return parameter ; } @Override public List < Extension > getAdditionalExtensions () { return Collections . singletonList ( new ParameterResolver () { @Override public boolean supportsParameter ( ParameterContext parameterContext , ExtensionContext extensionContext ) { return parameterContext . getParameter (). getType (). equals ( String . class ); } @Override public Object resolveParameter ( ParameterContext parameterContext , ExtensionContext extensionContext ) { return parameter ; } }); } }; } } In this example, the test template will be invoked twice. The display names of the invocations will be apple and banana as specified by the invocation context. Each invocation registers a custom ParameterResolver which is used to resolve the method parameter. The output when using the ConsoleLauncher is as follows.
└─ testTemplate(String) ✔ ├─ apple ✔ └─ banana ✔
The TestTemplateInvocationContextProvider extension API is primarily intended for implementing different kinds of tests that rely on repetitive invocation of a test-like method albeit in different contexts — for example, with different parameters, by preparing the test class instance differently, or multiple times without modifying the context. Please refer to the implementations of Repeated Tests or Parameterized Tests which use this extension point to provide their functionality.
5.13. Keeping State in Extensions
Usually, an extension is instantiated only once. So the question becomes relevant: How do you keep the state from one invocation of an extension to the next? The ExtensionContext API provides a Store exactly for this purpose. Extensions may put values into a store for later retrieval. See the TimingExtension for an example of using the Store with a method-level scope. It is important to remember that values stored in an ExtensionContext during test execution will not be available in the surrounding ExtensionContext. Since ExtensionContexts may be nested, the scope of inner contexts may also be limited. Consult the corresponding Javadoc for details on the methods available for storing and retrieving values via the Store.
| CloseableResource are notified by an invocation of their close() method in the inverse order they were added in. |
5.14. Supported Utilities in Extensions
The junit-platform-commons artifact exposes a package named org.junit.platform.commons.support that contains maintained utility methods for working with annotations, classes, reflection, and classpath scanning tasks. TestEngine and Extension authors are encouraged to use these supported methods in order to align with the behavior of the JUnit Platform.
5.14.1. Annotation Support
AnnotationSupport provides static utility methods that operate on annotated elements (e.g., packages, annotations, classes, interfaces, constructors, methods, and fields). These include methods to check whether an element is annotated or meta-annotated with a particular annotation, to search for specific annotations, and to find annotated methods and fields in a class or interface. Some of these methods search on implemented interfaces and within class hierarchies to find annotations. Consult the Javadoc for AnnotationSupport for further details.
5.14.2. Class Support
ClassSupport provides static utility methods for working with classes (i.e., instances of java.lang.Class). Consult the Javadoc for ClassSupport for further details.
5.14.3. Reflection Support
ReflectionSupport provides static utility methods that augment the standard JDK reflection and class-loading mechanisms. These include methods to scan the classpath in search of classes matching specified predicates, to load and create new instances of a class, and to find and invoke methods. Some of these methods traverse class hierarchies to locate matching methods. Consult the Javadoc for ReflectionSupport for further details.
5.14.4. Modifier Support
ModifierSupport provides static utility methods for working with member and class modifiers — for example, to determine if a member is declared as public, private, abstract, static, etc. Consult the Javadoc for ModifierSupport for further details.
5.15. Relative Execution Order of User Code and Extensions
When executing a test class that contains one or more test methods, a number of extension callbacks are called in addition to the user-supplied test and lifecycle methods.
| See also: Test Execution Order |
5.15.1. User and Extension Code
The following diagram illustrates the relative order of user-supplied code and extension code. User-supplied test and lifecycle methods are shown in orange, with callback code implemented by extensions shown in blue. The grey box denotes the execution of a single test method and will be repeated for every test method in the test class.
User code and extension code
The following table further explains the sixteen steps in the User code and extension code diagram.
| Step | Interface/Annotation | Description |
|---|---|---|
| 1 | interface | extension code executed before all tests of the container are executed |
| 2 | annotation | user code executed before all tests of the container are executed |
| 3 | interface | extension code for handling exceptions thrown from |
| 4 | interface | extension code executed before each test is executed |
| 5 | annotation | user code executed before each test is executed |
| 6 | interface | extension code for handling exceptions thrown from |
| 7 | interface | extension code executed immediately before a test is executed |
| 8 | annotation | user code of the actual test method |
| 9 | interface | extension code for handling exceptions thrown during a test |
| 10 | interface | extension code executed immediately after test execution and its corresponding exception handlers |
| 11 | annotation | user code executed after each test is executed |
| 12 | interface | extension code for handling exceptions thrown from |
| 13 | interface | extension code executed after each test is executed |
| 14 | annotation | user code executed after all tests of the container are executed |
| 15 | interface | extension code for handling exceptions thrown from |
| 16 | interface | extension code executed after all tests of the container are executed |
In the simplest case only the actual test method will be executed (step 8); all other steps are optional depending on the presence of user code or extension support for the corresponding lifecycle callback. For further details on the various lifecycle callbacks please consult the respective Javadoc for each annotation and extension.
All invocations of user code methods in the above table can additionally be intercepted by implementing InvocationInterceptor.
5.15.2. Wrapping Behavior of Callbacks
JUnit Jupiter always guarantees wrapping behavior for multiple registered extensions that implement lifecycle callbacks such as BeforeAllCallback, AfterAllCallback, BeforeEachCallback, AfterEachCallback, BeforeTestExecutionCallback, and AfterTestExecutionCallback.
That means that, given two extensions Extension1 and Extension2 with Extension1 registered before Extension2, any "before" callbacks implemented by Extension1 are guaranteed to execute before any "before" callbacks implemented by Extension2. Similarly, given the two same two extensions registered in the same order, any "after" callbacks implemented by Extension1 are guaranteed to execute after any "after" callbacks implemented by Extension2. Extension1 is therefore said to wrap Extension2.
JUnit Jupiter also guarantees wrapping behavior within class and interface hierarchies for user-supplied lifecycle methods (see Test Classes and Methods).
-
@BeforeAllmethods are inherited from superclasses as long as they are not hidden or overridden. Furthermore,@BeforeAllmethods from superclasses will be executed before@BeforeAllmethods in subclasses.-
Similarly,
@BeforeAllmethods declared in an interface are inherited as long as they are not hidden or overridden, and@BeforeAllmethods from an interface will be executed before@BeforeAllmethods in the class that implements the interface.
-
-
@AfterAllmethods are inherited from superclasses as long as they are not hidden or overridden. Furthermore,@AfterAllmethods from superclasses will be executed after@AfterAllmethods in subclasses.-
Similarly,
@AfterAllmethods declared in an interface are inherited as long as they are not hidden or overridden, and@AfterAllmethods from an interface will be executed after@AfterAllmethods in the class that implements the interface.
-
-
@BeforeEachmethods are inherited from superclasses as long as they are not overridden. Furthermore,@BeforeEachmethods from superclasses will be executed before@BeforeEachmethods in subclasses.-
Similarly,
@BeforeEachmethods declared as interface default methods are inherited as long as they are not overridden, and@BeforeEachdefault methods will be executed before@BeforeEachmethods in the class that implements the interface.
-
-
@AfterEachmethods are inherited from superclasses as long as they are not overridden. Furthermore,@AfterEachmethods from superclasses will be executed after@AfterEachmethods in subclasses.-
Similarly,
@AfterEachmethods declared as interface default methods are inherited as long as they are not overridden, and@AfterEachdefault methods will be executed after@AfterEachmethods in the class that implements the interface.
-
The following examples demonstrate this behavior. Please note that the examples do not actually do anything realistic. Instead, they mimic common scenarios for testing interactions with the database. All methods imported statically from the Logger class log contextual information in order to help us better understand the execution order of user-supplied callback methods and callback methods in extensions.
Extension1
import static example . callbacks . Logger . afterEachCallback ; import static example . callbacks . Logger . beforeEachCallback ; import org.junit.jupiter.api.extension.AfterEachCallback ; import org.junit.jupiter.api.extension.BeforeEachCallback ; import org.junit.jupiter.api.extension.ExtensionContext ; public class Extension1 implements BeforeEachCallback , AfterEachCallback { @Override public void beforeEach ( ExtensionContext context ) { beforeEachCallback ( this ); } @Override public void afterEach ( ExtensionContext context ) { afterEachCallback ( this ); } } Extension2
import static example . callbacks . Logger . afterEachCallback ; import static example . callbacks . Logger . beforeEachCallback ; import org.junit.jupiter.api.extension.AfterEachCallback ; import org.junit.jupiter.api.extension.BeforeEachCallback ; import org.junit.jupiter.api.extension.ExtensionContext ; public class Extension2 implements BeforeEachCallback , AfterEachCallback { @Override public void beforeEach ( ExtensionContext context ) { beforeEachCallback ( this ); } @Override public void afterEach ( ExtensionContext context ) { afterEachCallback ( this ); } } AbstractDatabaseTests
import static example . callbacks . Logger . afterAllMethod ; import static example . callbacks . Logger . afterEachMethod ; import static example . callbacks . Logger . beforeAllMethod ; import static example . callbacks . Logger . beforeEachMethod ; import org.junit.jupiter.api.AfterAll ; import org.junit.jupiter.api.AfterEach ; import org.junit.jupiter.api.BeforeAll ; import org.junit.jupiter.api.BeforeEach ; /** * Abstract base class for tests that use the database. */ abstract class AbstractDatabaseTests { @BeforeAll static void createDatabase () { beforeAllMethod ( AbstractDatabaseTests . class . getSimpleName () + ".createDatabase()" ); } @BeforeEach void connectToDatabase () { beforeEachMethod ( AbstractDatabaseTests . class . getSimpleName () + ".connectToDatabase()" ); } @AfterEach void disconnectFromDatabase () { afterEachMethod ( AbstractDatabaseTests . class . getSimpleName () + ".disconnectFromDatabase()" ); } @AfterAll static void destroyDatabase () { afterAllMethod ( AbstractDatabaseTests . class . getSimpleName () + ".destroyDatabase()" ); } } DatabaseTestsDemo
import static example . callbacks . Logger . afterEachMethod ; import static example . callbacks . Logger . beforeAllMethod ; import static example . callbacks . Logger . beforeEachMethod ; import static example . callbacks . Logger . testMethod ; import org.junit.jupiter.api.AfterAll ; import org.junit.jupiter.api.AfterEach ; import org.junit.jupiter.api.BeforeAll ; import org.junit.jupiter.api.BeforeEach ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.extension.ExtendWith ; /** * Extension of {@link AbstractDatabaseTests} that inserts test data * into the database (after the database connection has been opened) * and deletes test data (before the database connection is closed). */ @ExtendWith ({ Extension1 . class , Extension2 . class }) class DatabaseTestsDemo extends AbstractDatabaseTests { @BeforeAll static void beforeAll () { beforeAllMethod ( DatabaseTestsDemo . class . getSimpleName () + ".beforeAll()" ); } @BeforeEach void insertTestDataIntoDatabase () { beforeEachMethod ( getClass (). getSimpleName () + ".insertTestDataIntoDatabase()" ); } @Test void testDatabaseFunctionality () { testMethod ( getClass (). getSimpleName () + ".testDatabaseFunctionality()" ); } @AfterEach void deleteTestDataFromDatabase () { afterEachMethod ( getClass (). getSimpleName () + ".deleteTestDataFromDatabase()" ); } @AfterAll static void afterAll () { beforeAllMethod ( DatabaseTestsDemo . class . getSimpleName () + ".afterAll()" ); } } When the DatabaseTestsDemo test class is executed, the following is logged.
@BeforeAll AbstractDatabaseTests.createDatabase() @BeforeAll DatabaseTestsDemo.beforeAll() Extension1.beforeEach() Extension2.beforeEach() @BeforeEach AbstractDatabaseTests.connectToDatabase() @BeforeEach DatabaseTestsDemo.insertTestDataIntoDatabase() @Test DatabaseTestsDemo.testDatabaseFunctionality() @AfterEach DatabaseTestsDemo.deleteTestDataFromDatabase() @AfterEach AbstractDatabaseTests.disconnectFromDatabase() Extension2.afterEach() Extension1.afterEach() @BeforeAll DatabaseTestsDemo.afterAll() @AfterAll AbstractDatabaseTests.destroyDatabase()
The following sequence diagram helps to shed further light on what actually goes on within the JupiterTestEngine when the DatabaseTestsDemo test class is executed.
DatabaseTestsDemo
JUnit Jupiter does not guarantee the execution order of multiple lifecycle methods that are declared within a single test class or test interface. It may at times appear that JUnit Jupiter invokes such methods in alphabetical order. However, that is not precisely true. The ordering is analogous to the ordering for @Test methods within a single test class.
| Lifecycle methods that are declared within a single test class or test interface will be ordered using an algorithm that is deterministic but intentionally non-obvious. This ensures that subsequent runs of a test suite execute lifecycle methods in the same order, thereby allowing for repeatable builds. |
In addition, JUnit Jupiter does not support wrapping behavior for multiple lifecycle methods declared within a single test class or test interface.
The following example demonstrates this behavior. Specifically, the lifecycle method configuration is broken due to the order in which the locally declared lifecycle methods are executed.
-
Test data is inserted before the database connection has been opened, which results in a failure to connect to the database.
-
The database connection is closed before deleting the test data, which results in a failure to connect to the database.
BrokenLifecycleMethodConfigDemo
import static example . callbacks . Logger . afterEachMethod ; import static example . callbacks . Logger . beforeEachMethod ; import static example . callbacks . Logger . testMethod ; import org.junit.jupiter.api.AfterEach ; import org.junit.jupiter.api.BeforeEach ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.extension.ExtendWith ; /** * Example of "broken" lifecycle method configuration. * * <p>Test data is inserted before the database connection has been opened. * * <p>Database connection is closed before deleting test data. */ @ExtendWith ({ Extension1 . class , Extension2 . class }) class BrokenLifecycleMethodConfigDemo { @BeforeEach void connectToDatabase () { beforeEachMethod ( getClass (). getSimpleName () + ".connectToDatabase()" ); } @BeforeEach void insertTestDataIntoDatabase () { beforeEachMethod ( getClass (). getSimpleName () + ".insertTestDataIntoDatabase()" ); } @Test void testDatabaseFunctionality () { testMethod ( getClass (). getSimpleName () + ".testDatabaseFunctionality()" ); } @AfterEach void deleteTestDataFromDatabase () { afterEachMethod ( getClass (). getSimpleName () + ".deleteTestDataFromDatabase()" ); } @AfterEach void disconnectFromDatabase () { afterEachMethod ( getClass (). getSimpleName () + ".disconnectFromDatabase()" ); } } When the BrokenLifecycleMethodConfigDemo test class is executed, the following is logged.
Extension1.beforeEach() Extension2.beforeEach() @BeforeEach BrokenLifecycleMethodConfigDemo.insertTestDataIntoDatabase() @BeforeEach BrokenLifecycleMethodConfigDemo.connectToDatabase() @Test BrokenLifecycleMethodConfigDemo.testDatabaseFunctionality() @AfterEach BrokenLifecycleMethodConfigDemo.disconnectFromDatabase() @AfterEach BrokenLifecycleMethodConfigDemo.deleteTestDataFromDatabase() Extension2.afterEach() Extension1.afterEach()
The following sequence diagram helps to shed further light on what actually goes on within the JupiterTestEngine when the BrokenLifecycleMethodConfigDemo test class is executed.
BrokenLifecycleMethodConfigDemo
| Due to the aforementioned behavior, the JUnit Team recommends that developers declare at most one of each type of lifecycle method (see Test Classes and Methods) per test class or test interface unless there are no dependencies between such lifecycle methods. |
6. Advanced Topics
6.1. JUnit Platform Launcher API
One of the prominent goals of JUnit 5 is to make the interface between JUnit and its programmatic clients – build tools and IDEs – more powerful and stable. The purpose is to decouple the internals of discovering and executing tests from all the filtering and configuration that's necessary from the outside.
JUnit 5 introduces the concept of a Launcher that can be used to discover, filter, and execute tests. Moreover, third party test libraries – like Spock, Cucumber, and FitNesse – can plug into the JUnit Platform's launching infrastructure by providing a custom TestEngine.
6.1.1. Discovering Tests
Having test discovery as a dedicated feature of the platform itself frees IDEs and build tools from most of the difficulties they had to go through to identify test classes and test methods in previous versions of JUnit.
Usage Example:
import static org . junit . platform . engine . discovery . ClassNameFilter . includeClassNamePatterns ; import static org . junit . platform . engine . discovery . DiscoverySelectors . selectClass ; import static org . junit . platform . engine . discovery . DiscoverySelectors . selectPackage ; import java.io.PrintWriter ; import java.nio.file.Path ; import java.nio.file.Paths ; import org.junit.platform.engine.FilterResult ; import org.junit.platform.engine.TestDescriptor ; import org.junit.platform.launcher.Launcher ; import org.junit.platform.launcher.LauncherDiscoveryListener ; import org.junit.platform.launcher.LauncherDiscoveryRequest ; import org.junit.platform.launcher.LauncherSession ; import org.junit.platform.launcher.LauncherSessionListener ; import org.junit.platform.launcher.PostDiscoveryFilter ; import org.junit.platform.launcher.TestExecutionListener ; import org.junit.platform.launcher.TestPlan ; import org.junit.platform.launcher.core.LauncherConfig ; import org.junit.platform.launcher.core.LauncherDiscoveryRequestBuilder ; import org.junit.platform.launcher.core.LauncherFactory ; import org.junit.platform.launcher.listeners.SummaryGeneratingListener ; import org.junit.platform.launcher.listeners.TestExecutionSummary ; import org.junit.platform.reporting.legacy.xml.LegacyXmlReportGeneratingListener ; LauncherDiscoveryRequest request = LauncherDiscoveryRequestBuilder . request () . selectors ( selectPackage ( "com.example.mytests" ), selectClass ( MyTestClass . class ) ) . filters ( includeClassNamePatterns ( ".*Tests" ) ) . build (); try ( LauncherSession session = LauncherFactory . openSession ()) { TestPlan testPlan = session . getLauncher (). discover ( request ); // ... discover additional test plans or execute tests } You can select classes, methods, and all classes in a package or even search for all tests in the class-path or module-path. Discovery takes place across all participating test engines.
The resulting TestPlan is a hierarchical (and read-only) description of all engines, classes, and test methods that fit the LauncherDiscoveryRequest. The client can traverse the tree, retrieve details about a node, and get a link to the original source (like class, method, or file position). Every node in the test plan has a unique ID that can be used to invoke a particular test or group of tests.
Clients can register one or more LauncherDiscoveryListener implementations via the LauncherDiscoveryRequestBuilder to gain insight into events that occur during test discovery. By default, the builder registers an "abort on failure" listener that aborts test discovery after the first discovery failure is encountered. The default LauncherDiscoveryListener can be changed via the junit.platform.discovery.listener.default configuration parameter.
6.1.2. Executing Tests
To execute tests, clients can use the same LauncherDiscoveryRequest as in the discovery phase or create a new request. Test progress and reporting can be achieved by registering one or more TestExecutionListener implementations with the Launcher as in the following example.
LauncherDiscoveryRequest request = LauncherDiscoveryRequestBuilder . request () . selectors ( selectPackage ( "com.example.mytests" ), selectClass ( MyTestClass . class ) ) . filters ( includeClassNamePatterns ( ".*Tests" ) ) . build (); SummaryGeneratingListener listener = new SummaryGeneratingListener (); try ( LauncherSession session = LauncherFactory . openSession ()) { Launcher launcher = session . getLauncher (); // Register a listener of your choice launcher . registerTestExecutionListeners ( listener ); // Discover tests and build a test plan TestPlan testPlan = launcher . discover ( request ); // Execute test plan launcher . execute ( testPlan ); // Alternatively, execute the request directly launcher . execute ( request ); } TestExecutionSummary summary = listener . getSummary (); // Do something with the summary... 6.1.3. Registering a TestEngine
JUnit provides three TestEngine implementations.
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junit-jupiter-engine: The core of JUnit Jupiter. -
junit-vintage-engine: A thin layer on top of JUnit 4 to allow running vintage tests with the launcher infrastructure. -
junit-platform-suite-engine: To execute declarative suites of tests with the launcher infrastructure.
Third parties may also contribute their own TestEngine by implementing the interfaces in the junit-platform-engine module and registering their engine. Engine registration is supported via Java's ServiceLoader mechanism. For example, the junit-jupiter-engine module registers its org.junit.jupiter.engine.JupiterTestEngine in a file named org.junit.platform.engine.TestEngine within the /META-INF/services folder in the junit-jupiter-engine JAR.
HierarchicalTestEngine is a convenient abstract base implementation (used by the junit-jupiter-engine) that only requires implementors to provide the logic for test discovery. It implements execution of TestDescriptors that implement the Node interface, including support for parallel execution. |
| The The JUnit Platform
|
6.1.4. Registering a PostDiscoveryFilter
In addition to specifying post-discovery filters as part of a LauncherDiscoveryRequest passed to the Launcher API, PostDiscoveryFilter implementations will be discovered at runtime via Java's ServiceLoader mechanism and automatically applied by the Launcher in addition to those that are part of the request.
For example, an example.CustomTagFilter class implementing PostDiscoveryFilter and declared within the /META-INF/services/org.junit.platform.launcher.PostDiscoveryFilter file is loaded and applied automatically.
6.1.5. Registering a LauncherSessionListener
Registered implementations of LauncherSessionListener are notified when a LauncherSession is opened (before a Launcher first discovers and executes tests) and closed (when no more tests will be discovered or executed). They can be registered programmatically via the LauncherConfig that is passed to the LauncherFactory, or they can be discovered at runtime via Java's ServiceLoader mechanism and automatically registered with LauncherSession (unless automatic registration is disabled.)
A LauncherSessionListener is well suited for implementing once-per-JVM setup/teardown behavior since it's called before the first and after the last test in a launcher session, respectively. The scope of a launcher session depends on the used IDE or build tool but usually corresponds to the lifecycle of the test JVM. A custom listener that starts an HTTP server before executing the first test and stops it after the last test has been executed, could look like this:
src/test/java/example/session/GlobalSetupTeardownListener.java
package example.session ; import java.io.IOException ; import java.io.UncheckedIOException ; import java.net.InetSocketAddress ; import java.util.concurrent.ExecutorService ; import java.util.concurrent.Executors ; import com.sun.net.httpserver.HttpServer ; import org.junit.platform.launcher.LauncherSession ; import org.junit.platform.launcher.LauncherSessionListener ; import org.junit.platform.launcher.TestExecutionListener ; import org.junit.platform.launcher.TestPlan ; public class GlobalSetupTeardownListener implements LauncherSessionListener { private Fixture fixture ; @Override public void launcherSessionOpened ( LauncherSession session ) { // Avoid setup for test discovery by delaying it until tests are about to be executed session . getLauncher (). registerTestExecutionListeners ( new TestExecutionListener () { @Override public void testPlanExecutionStarted ( TestPlan testPlan ) { if ( fixture == null ) { fixture = new Fixture (); fixture . setUp (); } } }); } @Override public void launcherSessionClosed ( LauncherSession session ) { if ( fixture != null ) { fixture . tearDown (); fixture = null ; } } static class Fixture { private HttpServer server ; private ExecutorService executorService ; void setUp () { try { server = HttpServer . create ( new InetSocketAddress ( 0 ), 0 ); } catch ( IOException e ) { throw new UncheckedIOException ( "Failed to start HTTP server" , e ); } server . createContext ( "/test" , exchange -> { exchange . sendResponseHeaders ( 204 , - 1 ); exchange . close (); }); executorService = Executors . newCachedThreadPool (); server . setExecutor ( executorService ); server . start (); (1) int port = server . getAddress (). getPort (); System . setProperty ( "http.server.port" , String . valueOf ( port )); (2) } void tearDown () { server . stop ( 0 ); (3) executorService . shutdownNow (); } } } | 1 | Start the HTTP server |
| 2 | Export its dynamic port as a system property for consumption by tests |
| 3 | Stop the HTTP server |
This sample uses the HTTP server implementation from the jdk.httpserver module that comes with the JDK but would work similarly with any other server or resource. In order for the listener to be picked up by JUnit Platform, you need to register it as a service by adding a resource file with the following name and contents to your test runtime classpath (e.g. by adding the file to src/test/resources):
src/test/resources/META-INF/services/org.junit.platform.launcher.LauncherSessionListener
example.session.GlobalSetupTeardownListener You can now use the resource from your test:
src/test/java/example/session/HttpTests.java
package example.session ; import static org . junit . jupiter . api . Assertions . assertEquals ; import java.net.HttpURLConnection ; import java.net.URL ; import org.junit.jupiter.api.Test ; class HttpTests { @Test void respondsWith204 () throws Exception { String port = System . getProperty ( "http.server.port" ); (1) URL url = new URL ( "http://localhost:" + port + "/test" ); HttpURLConnection connection = ( HttpURLConnection ) url . openConnection (); connection . setRequestMethod ( "GET" ); int responseCode = connection . getResponseCode (); (2) assertEquals ( 204 , responseCode ); (3) } } | 1 | Read the port of the server from the system property set by the listener |
| 2 | Send a request to the server |
| 3 | Check the status code of the response |
6.1.6. Registering a LauncherDiscoveryListener
In addition to specifying discovery listeners as part of a LauncherDiscoveryRequest or registering them programmatically via the Launcher API, custom LauncherDiscoveryListener implementations can be discovered at runtime via Java's ServiceLoader mechanism and automatically registered with the Launcher created via the LauncherFactory.
For example, an example.CustomLauncherDiscoveryListener class implementing LauncherDiscoveryListener and declared within the /META-INF/services/org.junit.platform.launcher.LauncherDiscoveryListener file is loaded and registered automatically.
6.1.7. Registering a TestExecutionListener
In addition to the public Launcher API method for registering test execution listeners programmatically, custom TestExecutionListener implementations will be discovered at runtime via Java's ServiceLoader mechanism and automatically registered with the Launcher created via the LauncherFactory.
For example, an example.CustomTestExecutionListener class implementing TestExecutionListener and declared within the /META-INF/services/org.junit.platform.launcher.TestExecutionListener file is loaded and registered automatically.
6.1.8. Configuring a TestExecutionListener
When a TestExecutionListener is registered programmatically via the Launcher API, the listener may provide programmatic ways for it to be configured — for example, via its constructor, setter methods, etc. However, when a TestExecutionListener is registered automatically via Java's ServiceLoader mechanism (see Registering a TestExecutionListener), there is no way for the user to directly configure the listener. In such cases, the author of a TestExecutionListener may choose to make the listener configurable via configuration parameters. The listener can then access the configuration parameters via the TestPlan supplied to the testPlanExecutionStarted(TestPlan) and testPlanExecutionFinished(TestPlan) callback methods. See the UniqueIdTrackingListener for an example.
6.1.9. Deactivating a TestExecutionListener
Sometimes it can be useful to run a test suite without certain execution listeners being active. For example, you might have custom a TestExecutionListener that sends the test results to an external system for reporting purposes, and while debugging you might not want these debug results to be reported. To do this, provide a pattern for the junit.platform.execution.listeners.deactivate configuration parameter to specify which execution listeners should be deactivated (i.e. not registered) for the current test run.
| Only listeners registered via the In addition, since execution listeners are registered before the test run starts, the |
Pattern Matching Syntax
Refer to Pattern Matching Syntax for details.
6.1.10. Configuring the Launcher
If you require fine-grained control over automatic detection and registration of test engines and listeners, you may create an instance of LauncherConfig and supply that to the LauncherFactory. Typically, an instance of LauncherConfig is created via the built-in fluent builder API, as demonstrated in the following example.
LauncherConfig launcherConfig = LauncherConfig . builder () . enableTestEngineAutoRegistration ( false ) . enableLauncherSessionListenerAutoRegistration ( false ) . enableLauncherDiscoveryListenerAutoRegistration ( false ) . enablePostDiscoveryFilterAutoRegistration ( false ) . enableTestExecutionListenerAutoRegistration ( false ) . addTestEngines ( new CustomTestEngine ()) . addLauncherSessionListeners ( new CustomLauncherSessionListener ()) . addLauncherDiscoveryListeners ( new CustomLauncherDiscoveryListener ()) . addPostDiscoveryFilters ( new CustomPostDiscoveryFilter ()) . addTestExecutionListeners ( new LegacyXmlReportGeneratingListener ( reportsDir , out )) . addTestExecutionListeners ( new CustomTestExecutionListener ()) . build (); LauncherDiscoveryRequest request = LauncherDiscoveryRequestBuilder . request () . selectors ( selectPackage ( "com.example.mytests" )) . build (); try ( LauncherSession session = LauncherFactory . openSession ( launcherConfig )) { session . getLauncher (). execute ( request ); } 6.2. JUnit Platform Reporting
The junit-platform-reporting artifact contains TestExecutionListener implementations that generate test reports. These listeners are typically used by IDEs and build tools. The package org.junit.platform.reporting.legacy.xml currently contains the following implementation.
-
LegacyXmlReportGeneratingListenergenerates a separate XML report for each root in theTestPlan. Note that the generated XML format is compatible with the de facto standard for JUnit 4 based test reports that was made popular by the Ant build system. TheLegacyXmlReportGeneratingListeneris used by the Console Launcher as well.
The junit-platform-launcher module also contains TestExecutionListener implementations that can be used for reporting purposes. See Using Listeners for details. |
6.3. JUnit Platform Suite Engine
The JUnit Platform supports the declarative definition and execution of suites of tests from any test engine using the JUnit Platform.
6.3.1. Setup
In addition to the junit-platform-suite-api and junit-platform-suite-engine artifacts, you need at least one other test engine and its dependencies on the classpath. See Dependency Metadata for details regarding group IDs, artifact IDs, and versions.
Required Dependencies
-
junit-platform-suite-apiin test scope: artifact containing annotations needed to configure a test suite -
junit-platform-suite-enginein test runtime scope: implementation of theTestEngineAPI for declarative test suites
Both of the required dependencies are aggregated in the junit-platform-suite artifact which can be declard in test scope instead of declaring explicit dependencies on junit-platform-suite-api and junit-platform-suite-engine. |
Transitive Dependencies
-
junit-platform-suite-commonsin test scope -
junit-platform-launcherin test scope -
junit-platform-enginein test scope -
junit-platform-commonsin test scope -
opentest4jin test scope
6.3.2. @Suite Example
By annotating a class with @Suite it is marked as a test suite on the JUnit Platform. As seen in the following example, selector and filter annotations can then be used to control the contents of the suite.
import org.junit.platform.suite.api.IncludeClassNamePatterns ; import org.junit.platform.suite.api.SelectPackages ; import org.junit.platform.suite.api.Suite ; import org.junit.platform.suite.api.SuiteDisplayName ; @Suite @SuiteDisplayName ( "JUnit Platform Suite Demo" ) @SelectPackages ( "example" ) @IncludeClassNamePatterns ( ".*Tests" ) class SuiteDemo { } | Additional Configuration Options There are numerous configuration options for discovering and filtering tests in a test suite. Please consult the Javadoc of theorg.junit.platform.suite.api package for a full list of supported annotations and further details. |
6.4. JUnit Platform Test Kit
The junit-platform-testkit artifact provides support for executing a test plan on the JUnit Platform and then verifying the expected results. As of JUnit Platform 1.4, this support is limited to the execution of a single TestEngine (see Engine Test Kit).
6.4.1. Engine Test Kit
The org.junit.platform.testkit.engine package provides support for executing a TestPlan for a given TestEngine running on the JUnit Platform and then accessing the results via a fluent API to verify the expected results. The key entry point into this API is the EngineTestKit which provides static factory methods named engine() and execute(). It is recommended that you select one of the engine() variants to benefit from the fluent API for building a LauncherDiscoveryRequest.
If you prefer to use the LauncherDiscoveryRequestBuilder from the Launcher API to build your LauncherDiscoveryRequest, you must use one of the execute() variants in EngineTestKit. |
The following test class written using JUnit Jupiter will be used in subsequent examples.
import static org . junit . jupiter . api . Assertions . assertEquals ; import static org . junit . jupiter . api . Assumptions . assumeTrue ; import example.util.Calculator ; import org.junit.jupiter.api.Disabled ; import org.junit.jupiter.api.MethodOrderer.OrderAnnotation ; import org.junit.jupiter.api.Order ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.TestMethodOrder ; @TestMethodOrder ( OrderAnnotation . class ) public class ExampleTestCase { private final Calculator calculator = new Calculator (); @Test @Disabled ( "for demonstration purposes" ) @Order ( 1 ) void skippedTest () { // skipped ... } @Test @Order ( 2 ) void succeedingTest () { assertEquals ( 42 , calculator . multiply ( 6 , 7 )); } @Test @Order ( 3 ) void abortedTest () { assumeTrue ( "abc" . contains ( "Z" ), "abc does not contain Z" ); // aborted ... } @Test @Order ( 4 ) void failingTest () { // The following throws an ArithmeticException: "/ by zero" calculator . divide ( 1 , 0 ); } } For the sake of brevity, the following sections demonstrate how to test JUnit's own JupiterTestEngine whose unique engine ID is "junit-jupiter". If you want to test your own TestEngine implementation, you need to use its unique engine ID. Alternatively, you may test your own TestEngine by supplying an instance of it to the EngineTestKit.engine(TestEngine) static factory method.
6.4.2. Asserting Statistics
One of the most common features of the Test Kit is the ability to assert statistics against events fired during the execution of a TestPlan. The following tests demonstrate how to assert statistics for containers and tests in the JUnit Jupiter TestEngine. For details on what statistics are available, consult the Javadoc for EventStatistics.
import static org . junit . platform . engine . discovery . DiscoverySelectors . selectClass ; import example.ExampleTestCase ; import org.junit.jupiter.api.Test ; import org.junit.platform.testkit.engine.EngineTestKit ; class EngineTestKitStatisticsDemo { @Test void verifyJupiterContainerStats () { EngineTestKit . engine ( "junit-jupiter" ) (1) . selectors ( selectClass ( ExampleTestCase . class )) (2) . execute () (3) . containerEvents () (4) . assertStatistics ( stats -> stats . started ( 2 ). succeeded ( 2 )); (5) } @Test void verifyJupiterTestStats () { EngineTestKit . engine ( "junit-jupiter" ) (1) . selectors ( selectClass ( ExampleTestCase . class )) (2) . execute () (3) . testEvents () (6) . assertStatistics ( stats -> stats . skipped ( 1 ). started ( 3 ). succeeded ( 1 ). aborted ( 1 ). failed ( 1 )); (7) } } | 1 | Select the JUnit Jupiter TestEngine. |
| 2 | Select the ExampleTestCase test class. |
| 3 | Execute the TestPlan. |
| 4 | Filter by container events. |
| 5 | Assert statistics for container events. |
| 6 | Filter by test events. |
| 7 | Assert statistics for test events. |
In the verifyJupiterContainerStats() test method, the counts for the started and succeeded statistics are 2 since the JupiterTestEngine and the ExampleTestCase class are both considered containers. |
6.4.3. Asserting Events
If you find that asserting statistics alone is insufficient for verifying the expected behavior of test execution, you can work directly with the recorded Event elements and perform assertions against them.
For example, if you want to verify the reason that the skippedTest() method in ExampleTestCase was skipped, you can do that as follows.
| The For details on what conditions are available for use with AssertJ assertions against events, consult the Javadoc for |
import static org . junit . platform . engine . discovery . DiscoverySelectors . selectMethod ; import static org . junit . platform . testkit . engine . EventConditions . event ; import static org . junit . platform . testkit . engine . EventConditions . skippedWithReason ; import static org . junit . platform . testkit . engine . EventConditions . test ; import example.ExampleTestCase ; import org.junit.jupiter.api.Test ; import org.junit.platform.testkit.engine.EngineTestKit ; import org.junit.platform.testkit.engine.Events ; class EngineTestKitSkippedMethodDemo { @Test void verifyJupiterMethodWasSkipped () { String methodName = "skippedTest" ; Events testEvents = EngineTestKit (5) . engine ( "junit-jupiter" ) (1) . selectors ( selectMethod ( ExampleTestCase . class , methodName )) (2) . execute () (3) . testEvents (); (4) testEvents . assertStatistics ( stats -> stats . skipped ( 1 )); (6) testEvents . assertThatEvents () (7) . haveExactly ( 1 , event ( test ( methodName ), skippedWithReason ( "for demonstration purposes" ))); } } | 1 | Select the JUnit Jupiter TestEngine. |
| 2 | Select the skippedTest() method in the ExampleTestCase test class. |
| 3 | Execute the TestPlan. |
| 4 | Filter by test events. |
| 5 | Save the test Events to a local variable. |
| 6 | Optionally assert the expected statistics. |
| 7 | Assert that the recorded test events contain exactly one skipped test named skippedTest with "for demonstration purposes" as the reason. |
If you want to verify the type of exception thrown from the failingTest() method in ExampleTestCase, you can do that as follows.
import static org . junit . platform . engine . discovery . DiscoverySelectors . selectClass ; import static org . junit . platform . testkit . engine . EventConditions . event ; import static org . junit . platform . testkit . engine . EventConditions . finishedWithFailure ; import static org . junit . platform . testkit . engine . EventConditions . test ; import static org . junit . platform . testkit . engine . TestExecutionResultConditions . instanceOf ; import static org . junit . platform . testkit . engine . TestExecutionResultConditions . message ; import example.ExampleTestCase ; import org.junit.jupiter.api.Test ; import org.junit.platform.testkit.engine.EngineTestKit ; class EngineTestKitFailedMethodDemo { @Test void verifyJupiterMethodFailed () { EngineTestKit . engine ( "junit-jupiter" ) (1) . selectors ( selectClass ( ExampleTestCase . class )) (2) . execute () (3) . testEvents () (4) . assertThatEvents (). haveExactly ( 1 , (5) event ( test ( "failingTest" ), finishedWithFailure ( instanceOf ( ArithmeticException . class ), message ( "/ by zero" )))); } } | 1 | Select the JUnit Jupiter TestEngine. |
| 2 | Select the ExampleTestCase test class. |
| 3 | Execute the TestPlan. |
| 4 | Filter by test events. |
| 5 | Assert that the recorded test events contain exactly one failing test named failingTest with an exception of type ArithmeticException and an error message equal to "/ by zero". |
Although typically unnecessary, there are times when you need to verify all of the events fired during the execution of a TestPlan. The following test demonstrates how to achieve this via the assertEventsMatchExactly() method in the EngineTestKit API.
| Since |
If you want to do a partial match with or without ordering requirements, you can use the methods assertEventsMatchLooselyInOrder() and assertEventsMatchLoosely(), respectively.
import static org . junit . jupiter . api . condition . JRE . JAVA_18 ; import static org . junit . platform . engine . discovery . DiscoverySelectors . selectClass ; import static org . junit . platform . testkit . engine . EventConditions . abortedWithReason ; import static org . junit . platform . testkit . engine . EventConditions . container ; import static org . junit . platform . testkit . engine . EventConditions . engine ; import static org . junit . platform . testkit . engine . EventConditions . event ; import static org . junit . platform . testkit . engine . EventConditions . finishedSuccessfully ; import static org . junit . platform . testkit . engine . EventConditions . finishedWithFailure ; import static org . junit . platform . testkit . engine . EventConditions . skippedWithReason ; import static org . junit . platform . testkit . engine . EventConditions . started ; import static org . junit . platform . testkit . engine . EventConditions . test ; import static org . junit . platform . testkit . engine . TestExecutionResultConditions . instanceOf ; import static org . junit . platform . testkit . engine . TestExecutionResultConditions . message ; import java.io.StringWriter ; import java.io.Writer ; import example.ExampleTestCase ; import org.junit.jupiter.api.Test ; import org.junit.jupiter.api.condition.DisabledOnJre ; import org.junit.platform.testkit.engine.EngineTestKit ; import org.opentest4j.TestAbortedException ; class EngineTestKitAllEventsDemo { @Test @DisabledOnJre ( JAVA_18 ) // https://github.com/assertj/assertj-core/issues/2340 void verifyAllJupiterEvents () { Writer writer = // create a java.io.Writer for debug output EngineTestKit . engine ( "junit-jupiter" ) (1) . selectors ( selectClass ( ExampleTestCase . class )) (2) . execute () (3) . allEvents () (4) . debug ( writer ) (5) . assertEventsMatchExactly ( (6) event ( engine (), started ()), event ( container ( ExampleTestCase . class ), started ()), event ( test ( "skippedTest" ), skippedWithReason ( "for demonstration purposes" )), event ( test ( "succeedingTest" ), started ()), event ( test ( "succeedingTest" ), finishedSuccessfully ()), event ( test ( "abortedTest" ), started ()), event ( test ( "abortedTest" ), abortedWithReason ( instanceOf ( TestAbortedException . class ), message ( m -> m . contains ( "abc does not contain Z" )))), event ( test ( "failingTest" ), started ()), event ( test ( "failingTest" ), finishedWithFailure ( instanceOf ( ArithmeticException . class ), message ( "/ by zero" ))), event ( container ( ExampleTestCase . class ), finishedSuccessfully ()), event ( engine (), finishedSuccessfully ())); } } | 1 | Select the JUnit Jupiter TestEngine. |
| 2 | Select the ExampleTestCase test class. |
| 3 | Execute the TestPlan. |
| 4 | Filter by all events. |
| 5 | Print all events to the supplied writer for debugging purposes. Debug information can also be written to an OutputStream such as System.out or System.err. |
| 6 | Assert all events in exactly the order in which they were fired by the test engine. |
The debug() invocation from the preceding example results in output similar to the following.
All Events: Event [type = STARTED, testDescriptor = JupiterEngineDescriptor: [engine:junit-jupiter], timestamp = 2018-12-14T12:45:14.082280Z, payload = null] Event [type = STARTED, testDescriptor = ClassTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase], timestamp = 2018-12-14T12:45:14.089339Z, payload = null] Event [type = SKIPPED, testDescriptor = TestMethodTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase]/[method:skippedTest()], timestamp = 2018-12-14T12:45:14.094314Z, payload = 'for demonstration purposes'] Event [type = STARTED, testDescriptor = TestMethodTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase]/[method:succeedingTest()], timestamp = 2018-12-14T12:45:14.095182Z, payload = null] Event [type = FINISHED, testDescriptor = TestMethodTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase]/[method:succeedingTest()], timestamp = 2018-12-14T12:45:14.104922Z, payload = TestExecutionResult [status = SUCCESSFUL, throwable = null]] Event [type = STARTED, testDescriptor = TestMethodTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase]/[method:abortedTest()], timestamp = 2018-12-14T12:45:14.106121Z, payload = null] Event [type = FINISHED, testDescriptor = TestMethodTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase]/[method:abortedTest()], timestamp = 2018-12-14T12:45:14.109956Z, payload = TestExecutionResult [status = ABORTED, throwable = org.opentest4j.TestAbortedException: Assumption failed: abc does not contain Z]] Event [type = STARTED, testDescriptor = TestMethodTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase]/[method:failingTest()], timestamp = 2018-12-14T12:45:14.110680Z, payload = null] Event [type = FINISHED, testDescriptor = TestMethodTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase]/[method:failingTest()], timestamp = 2018-12-14T12:45:14.111217Z, payload = TestExecutionResult [status = FAILED, throwable = java.lang.ArithmeticException: / by zero]] Event [type = FINISHED, testDescriptor = ClassTestDescriptor: [engine:junit-jupiter]/[class:example.ExampleTestCase], timestamp = 2018-12-14T12:45:14.113731Z, payload = TestExecutionResult [status = SUCCESSFUL, throwable = null]] Event [type = FINISHED, testDescriptor = JupiterEngineDescriptor: [engine:junit-jupiter], timestamp = 2018-12-14T12:45:14.113806Z, payload = TestExecutionResult [status = SUCCESSFUL, throwable = null]] 7. API Evolution
One of the major goals of JUnit 5 is to improve maintainers' capabilities to evolve JUnit despite its being used in many projects. With JUnit 4 a lot of stuff that was originally added as an internal construct only got used by external extension writers and tool builders. That made changing JUnit 4 especially difficult and sometimes impossible.
That's why JUnit 5 introduces a defined lifecycle for all publicly available interfaces, classes, and methods.
7.1. API Version and Status
Every published artifact has a version number <major>.<minor>.<patch>, and all publicly available interfaces, classes, and methods are annotated with @API from the @API Guardian project. The annotation's status attribute can be assigned one of the following values.
| Status | Description |
|---|---|
| | Must not be used by any code other than JUnit itself. Might be removed without prior notice. |
| | Should no longer be used; might disappear in the next minor release. |
| | Intended for new, experimental features where we are looking for feedback. |
| | Intended for features that will not be changed in a backwards- incompatible way for at least the next minor release of the current major version. If scheduled for removal, it will be demoted to |
| | Intended for features that will not be changed in a backwards- incompatible way in the current major version ( |
If the @API annotation is present on a type, it is considered to be applicable for all public members of that type as well. A member is allowed to declare a different status value of lower stability.
7.2. Experimental APIs
The following table lists which APIs are currently designated as experimental via @API(status = EXPERIMENTAL). Caution should be taken when relying on such APIs.
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7.3. Deprecated APIs
The following table lists which APIs are currently designated as deprecated via @API(status = DEPRECATED). You should avoid using deprecated APIs whenever possible, since such APIs will likely be removed in an upcoming release.
| Package Name | Type Name | Since |
|---|---|---|
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7.4. @API Tooling Support
The @API Guardian project plans to provide tooling support for publishers and consumers of APIs annotated with @API. For example, the tooling support will likely provide a means to check if JUnit APIs are being used in accordance with @API annotation declarations.
8. Contributors
9. Release Notes
The release notes are available here.
10. Appendix
10.1. Reproducible Builds
Starting with version 5.7, JUnit 5 aims for its non-javadoc JARs to be reproducible.
Under identical build conditions, such as Java version, repeated builds should provide the same output byte-for-byte.
This means that anyone can reproduce the build conditions of the artifacts on Maven Central/Sonatype and produce the same output artifact locally, confirming that the artifacts in the repositories were actually generated from this source code.
10.2. Dependency Metadata
10.2.1. JUnit Platform
-
Group ID:
org.junit.platform -
Version:
1.8.1 -
Artifact IDs:
-
junit-platform-commons -
Common APIs and support utilities for the JUnit Platform. Any API annotated with
@API(status = INTERNAL)is intended solely for usage within the JUnit framework itself. Any usage of internal APIs by external parties is not supported! -
junit-platform-console -
Support for discovering and executing tests on the JUnit Platform from the console. See Console Launcher for details.
-
junit-platform-console-standalone -
An executable JAR with all dependencies included is provided in Maven Central under the junit-platform-console-standalone directory. See Console Launcher for details.
-
junit-platform-engine -
Public API for test engines. See Registering a TestEngine for details.
-
junit-platform-jfr -
Provides a
LauncherDiscoveryListenerandTestExecutionListenerfor Java Flight Recorder events on the JUnit Platform. See Flight Recorder Support for details. -
junit-platform-launcher -
Public API for configuring and launching test plans — typically used by IDEs and build tools. See JUnit Platform Launcher API for details.
-
junit-platform-reporting -
TestExecutionListenerimplementations that generate test reports — typically used by IDEs and build tools. See JUnit Platform Reporting for details. -
junit-platform-runner -
Runner for executing tests and test suites on the JUnit Platform in a JUnit 4 environment. See Using JUnit 4 to run the JUnit Platform for details.
-
junit-platform-suite -
JUnit Platform Suite artifact that transitively pulls in dependencies on
junit-platform-suite-apiandjunit-platform-suite-enginefor simplified dependency management in build tools such as Gradle and Maven. -
junit-platform-suite-api -
Annotations for configuring test suites on the JUnit Platform. Supported by the JUnit Platform Suite Engine and the JUnitPlatform runner.
-
junit-platform-suite-commons -
Common support utilities for executing test suites on the JUnit Platform.
-
junit-platform-suite-engine -
Engine that executes test suites on the JUnit Platform; only required at runtime. See JUnit Platform Suite Engine for details.
-
junit-platform-testkit -
Provides support for executing a test plan for a given
TestEngineand then accessing the results via a fluent API to verify the expected results.
-
10.2.2. JUnit Jupiter
-
Group ID:
org.junit.jupiter -
Version:
5.8.1 -
Artifact IDs:
-
junit-jupiter -
JUnit Jupiter aggregator artifact that transitively pulls in dependencies on
junit-jupiter-api,junit-jupiter-params, andjunit-jupiter-enginefor simplified dependency management in build tools such as Gradle and Maven. -
junit-jupiter-api -
JUnit Jupiter API for writing tests and extensions.
-
junit-jupiter-engine -
JUnit Jupiter test engine implementation; only required at runtime.
-
junit-jupiter-params -
Support for parameterized tests in JUnit Jupiter.
-
junit-jupiter-migrationsupport -
Support for migrating from JUnit 4 to JUnit Jupiter; only required for support for JUnit 4's
@Ignoreannotation and for running selected JUnit 4 rules.
-
10.2.3. JUnit Vintage
-
Group ID:
org.junit.vintage -
Version:
5.8.1 -
Artifact ID:
-
junit-vintage-engine -
JUnit Vintage test engine implementation that allows one to run vintage JUnit tests on the JUnit Platform. Vintage tests include those written using JUnit 3 or JUnit 4 APIs or tests written using testing frameworks built on those APIs.
-
10.2.4. Bill of Materials (BOM)
The Bill of Materials POM provided under the following Maven coordinates can be used to ease dependency management when referencing multiple of the above artifacts using Maven or Gradle.
-
Group ID:
org.junit -
Artifact ID:
junit-bom -
Version:
5.8.1
10.2.5. Dependencies
Most of the above artifacts have a dependency in their published Maven POMs on the following @API Guardian JAR.
-
Group ID:
org.apiguardian -
Artifact ID:
apiguardian-api -
Version:
1.1.2
In addition, most of the above artifacts have a direct or transitive dependency on the following OpenTest4J JAR.
-
Group ID:
org.opentest4j -
Artifact ID:
opentest4j -
Version:
1.2.0
10.3. Dependency Diagram
How To Create Junit Test Class In Intellij
Source: https://junit.org/junit5/docs/current/user-guide/
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