Java Integration Testing Guidelines

Apply Java 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

Before applying any integration test changes, ensure the project compiles. If compilation fails, stop immediately. After applying improvements, run full verification.

• MANDATORY: Run ./mvnw compile or mvn compile before applying any change
• SAFETY: If compilation fails, stop immediately
• VERIFY: Run ./mvnw clean verify or mvn clean verify after applying improvements
• BEFORE APPLYING: Read the reference for detailed rules and good/bad patterns

When to use this skill

• Review Java code for Spring Boot integration tests
• Apply best practices for Spring Boot integration tests in Java code

Reference

For detailed guidance, examples, and constraints, see references/322-frameworks-spring-boot-testing-integration-tests.md.