What are best practices for integration testing?

Integration tests verify component interactions. Best practices: use test databases (Docker containers), reset state between tests (transactions or cleanup), test real dependencies when feasible, mock external services (WireMock, VCR), use meaningful test data, separate from unit tests, run in CI pipeline. Test database interactions, API contracts, message queues. Balance with unit tests - slower but catch integration issues. Consider contract testing (Pact) for microservices.