Spring Boot TDD Patterns

Test-driven development workflow for Spring Boot 3.x with JUnit 5.

Test Pyramid

         /  E2E  \          <- Few, slow, high confidence
        / Integration \     <- Moderate, Testcontainers
       /  Slice Tests   \   <- Fast, focused (@WebMvcTest, @DataJpaTest)
      /   Unit Tests     \  <- Many, fastest, isolated

Unit Tests (Service Layer)

@ExtendWith(MockitoExtension.class)
class UserServiceTest {