JUnit 5

Java 8 necessary

Most used annotations

@Test
@BeforeEach
@BeforeAll
@AfterEach
@AfterAll
@Disabled

Test Method:
- any instance method that is directly annotated or meta-annotated with @Test, @RepeatedTest, @ParameterizedTest, @TestFactory, or @TestTemplate.
- not private
- not (more) required to be public

Meta-Annotations / Composed Annotations

Multiple annotations can be composed to one, which can be used later instead.

Example 1

Replace @Tag(“fast”) with @Fast

@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Tag("fast")
public @interface Fast {
}

Usage:

@Fast
@Test
void myFastTest() {
    // ...
}

Example 2

Combine @Tag(“fast”) and @Test to one @FastTest.

@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Tag("fast")
@Test
public @interface FastTest {
}

Usage:

@FastTest
void myFastTest() {
    // ...
}

Assertions

Using lambdas
Grouped assertions
Dependent assertions
Exception testing
Timeout not exceeded
- (simply)
- with result
- with method
Timeout exceeded
- (simply)
- with preemptive termination

Kotlin assertions support
Third party library support
- AssertJ
- Hamcrest
- Truth

Assumptions

In direct contrast to failed assertions, failed assumptions do not result in a test failure; rather, a failed assumption results in a test being aborted.

Assumptions are typically used whenever it does not make sense to continue execution of a given test method — for example, if the test depends on something that does not exist in the current runtime environment.

assumeTrue()
assumeFalse()
assumingThat()

Conditional Test Execution

@DisabledOnOs
@DisabledOnJre / @DisabledForJreRange
@DisabledIfEnvironmentVariable / @DisabledIfEnvironmentVariables
@DisabledIfSystemProperty / @DisabledIfSystemProperties
@EnabledOnOs
@EnabledOnJre / @EnabledForJreRange
@EnabledIfEnvironmentVariable / @EnabledIfEnvironmentVariables
@EnabledIfSystemProperty / @EnabledIfSystemProperties

Test Execution Order

@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
    }
 
}

Test Instance Lifecycle

Parameterized Tests

@ParameterizedTest

Repeated Tests

@RepeatedTest

Dynamic Tests

@TestFactory

Templates for Test Cases

@TestTemplate

Misc

@TestMethodOrder - defines test method execution order
@TestInstance - ???
@DisplayName - declares custom display name for test
@DisplayNameGeneration - declares custom display name generator
@Nested - ???
@Tag - makes possible grouping of tests either on class or on method level
@Timeout - used to fail tests, if their execution exceeds a given duration
@ExtendWith - ???
@RegisterExtension - ???
@TempDir - ???

JUnit 5 Pros

More granularity
Multiple runners work simultaneously
Java 8 language features

JUnit 4 -> JUnit 5

@Before → @BeforeEach
@After → @AfterEach
@BeforeClass → @BeforeAll
@AfterClass → @AfterAll
@Ignore → @Disabled

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