JUnit 5 from Basics to Advanced

Unit Testing in Java
What you'll learn
Unit Testing
JUnit5
Mockito
Java Testing Framework
Requirements
Java
Description
Unit testing roadmap
Topics already covered
- Available Frameworks
- Junit
- TestNG etc.
- What is a unit test?
- Difference between unit vs integration vs functional tests
- AAA (Arrange-Act-Assert)
- Maven/Gradle dependencies
- Test Lifecycle
- Basic Annotations
• @Test
• @BeforeEach, @AfterEach
• @BeforeAll, @AfterAll
• @DisplayName
• @Disable
etc.
- Assertions
• assertEquals, assertNotEquals
• assertTrue, assertFalse
• assertNull, assertNotNull
• assertThrows for exception testing
- Extensions
- Test Repetition
• @RepeatedTest
Upcoming
- Parameterized Tests
Mocking
- Available Frameworks
- Mockito
- EasyMock
- JMock
- Mockito Core Concepts
• @Mock and Mockito.mock(Class.class)
• @InjectMocks for injecting mocks
• @BeforeEach with MockitoAnnotations.openMocks(this)
• Testing Private/Static Methods (PowerMock or some other approach)
- Stubbing Behavior
• when(...).thenReturn(...)
• when(...).thenThrow(...)
- Verifying Calls
• verify(...) after method call
• verifyNoMoreInteractions(...)
- Void Method Stubbing
• doNothing().when(mock).method()
• doThrow(...).when(...)
- Argument Matchers
• any(), eq(), anyString(), anyInt(), etc.
• Mixing matchers with exact values (and why it fails)
- Behavior Verification
- Verify how many times called: times, never(), atLeastOnce()
- Spies vs Mocks
○ Mockito.spy() for partial mocking
○ Difference between mock() and spy()
- Testing Configuration, Properties, and Profiles
- Unit tests with different Spring profiles.
- How to mock @Value, Environment, or @ConfigurationProperties.
- Overriding properties for test-only behavior.
Assertions & Matchers
- Frameworks
- AssertJ
- Hamcrest
Some Advanced Topics
- Test-Driven Development (TDD)
- Write failing test first, then code
- Test Coverage
• Tools: JaCoCo, IntelliJ coverage tool
- CI integration
- Run tests in GitHub Actions, GitLab CI/CD, Jenkins.
- Test Reports
- Generate HTML/XML test reports for build tools.
AI + Unit Testing
- Code Suggestion Tools (AI-Powered IDE Extensions)
- Using AI in CI/CD (Future-Forward)
- AI suggests missing test cases for changed methods
- AI flags flaky or redundant tests
- Autogenerate Missing Tests
Who this course is for
Java Backend Developers
Homepage