Testcontainers for Spring Boot Tests

Own the real dependencies a test needs and their lifecycle. A containerized test is an infrastructure test: it is slower, it is order and resource sensitive, and it is the only test that can prove SQL, transactions, and protocol semantics.

When to use

• A test needs a real database, cache, broker, or cloud emulator instead of a double.
• Wiring @ServiceConnection or @DynamicPropertySource into a Spring test.
• Choosing an image tag, a distribution, and a version that matches production, or deciding whether to reuse locally.
• Seeding data, running migrations on container start, isolating parallel classes, or diagnosing a slow or flaky dependency test.

When not to use

• JUnit structure, parameterization, extensions, and tags belong to spring-boot-junit.
• Mock, spy, and fake design belong to spring-boot-mockito.
• Which layer a test belongs to belongs to spring-boot-integration-testing.
• Migration authoring and schema history rules belong to spring-boot-flyway.
• Pipeline runtime, caching, and stage gating belong to spring-boot-ci-cd.