Java Testing Advanced

This takes your Java testing beyond the basics with four power tools: Testcontainers for spinning up real Postgres or Kafka instances in Docker, Pact for consumer-driven contract testing between services, PIT for mutation testing that actually validates your test quality, and property-based testing for generating edge cases you wouldn't think of. The Testcontainers examples are solid, showing Spring Boot integration with dynamic properties. Mutation testing is where this gets interesting because it tells you if your tests would catch actual bugs, not just pass with green checkmarks. If you're doing microservices or need real integration tests without mocking everything to death, these techniques will save you from production surprises.