Spring Boot Integration Testing

Apply Spring Boot integration testing guidelines for Spring Boot 4.0.x.

What is covered in this Skill?

• Integration test scope and purpose (verify wiring and contracts, not unit-test duplication)
• Testcontainers with @ServiceConnection for zero-config wiring (preferred)
• @DynamicPropertySource as fallback for containers without built-in service connection support
• Static @Container instances shared across test methods for performance
• MockMvcTester for fluent AssertJ-based HTTP assertions (Spring Boot 4.0.x)
• TestRestTemplate for full HTTP stack testing
• @DataJdbcTest / @DataJpaTest persistence slices (load only persistence layer, start faster)
• Data isolation: each test owns its scenario; no shared mutable state or ordering assumptions
• @MockitoBean for mock registration (Spring Boot 4.0.x — @MockBean removed)
• Resource lifecycle: Testcontainers JUnit integration for teardown; *IT / integration test separation

Scope: Apply recommendations based on the reference rules and good/bad code examples.

Constraints