JUnit 5+ Tutorials

JUnit 5 quick start tutorial

Understanding JUnit 5 life cycle methods

JUnit 5 quick start tutorial.

Understanding assertions methods in Assertion class

Asserting equality

Assertions#assertSame() examples

Assertions#assertInstanceOf() example()

assertTrue/assertFalse examples

assertNull/assertNotNull examples

Asserting Array And Iterable Equality

Assertions#assertLinesMatch() examples

Assertions#assertAll() examples

Asserting exception examples

Timeout Assertions

Assertions#fail() example

Use of @Nullable in Assertion class

Understanding Assumptions

JUnit 5 Assumptions: assumeTrue and assumeFalse examples and usage.

JUnit 5 Assumptions: using assumingThat to run a block conditionally without aborting the whole test.

JUnit 5 Assumptions: aborting a test manually with Assumptions.abort(...); also shows throwAssumptionFailed(...)

JUnit 5 @DisplayName: give readable names to test classes and methods for reports and IDEs.

JUnit 5 DisplayNameGenerator: control how display names are generated for test classes and methods using built-in generators or a custom one.

Configure a global JUnit 5 DisplayNameGenerator using junit-platform.properties so all tests get readable names without annotating each class.

Implement a custom JUnit 5 DisplayNameGenerator to produce readable test names, and see how it interacts with @DisplayName and nested tests.

Use JUnit 5 @Disabled to skip tests temporarily at class or method level, with optional reasons.

Use @EnabledIfSystemProperty and @DisabledIfSystemProperty to run or skip tests based on JVM system properties.

Use @EnabledIfEnvironmentVariable and @DisabledIfEnvironmentVariable to run or skip tests depending on environment variables.

Use JUnit 5 @EnabledIf and @DisabledIf to conditionally run or skip tests based on boolean-returning methods.

Use @EnabledOnJre/@DisabledOnJre and range annotations to control test execution by Java runtime version.

Use @EnabledOnOs and @DisabledOnOs to conditionally run tests on Windows, Linux, macOS, and others.

Introduction to parameterized tests in JUnit Jupiter using @ParameterizedTest. Conceptual overview and Javadoc reference.

Using @ValueSource to supply arguments to parameterized tests in JUnit 5.

Using @CsvSource to supply multiple arguments to a parameterized test in JUnit 5.

Using @MethodSource to supply arguments from factory methods to parameterized tests in JUnit 5.

Using @CsvFileSource to read test data from CSV files in JUnit 5.

Using @EnumSource to provide enum constants to parameterized tests in JUnit 5.

Using a custom ArgumentsProvider via @ArgumentsSource to feed arguments to parameterized tests in JUnit 5.

Using SimpleArgumentConverter with @ConvertWith to convert input values in parameterized tests (JUnit 5).

Combine multiple sources for parameterized tests in JUnit 5.

Using @ParameterizedTest with @NullSource to provide a single null argument to parameterized tests in JUnit 5.

Using @EmptySource to provide empty values (like empty strings) to parameterized tests in JUnit 5.

Using @NullAndEmptySource to combine null and empty values for parameterized tests in JUnit 5.

Understanding the @TestInstance annotation and test lifecycle in JUnit 5.

Using @TestInstance default PER_METHOD lifecycle in JUnit 5.

Using @TestInstance(PER_CLASS) to share test instance across methods.

Comparing PER_METHOD and PER_CLASS lifecycles with practical examples.

Introduction to @Nested tests in JUnit 5 for organizing test classes.

Understanding @BeforeAll, @AfterAll, @BeforeEach, and @AfterEach in nested test classes.

How nested test classes inherit and share state from outer classes to avoid test setup duplication.

Customizing display names for nested test classes using @DisplayName annotation.

Combining @Nested classes with @ParameterizedTest for data-driven testing in hierarchical structures.

Implementing Given-When-Then / BDD pattern using JUnit 5 nested test classes.