Testing
Integration tests that mock the database are not integration tests. They are unit tests with extra ceremony. The moment you swap your real PostgreSQL for an in-memory SQLite, you stop testing the thing that breaks in production: your actual queries, your migrations, your transaction isolation, your Redis eviction behavior.
Redis
Testing code that depends on Redis presents a fundamental choice: simulate Redis in-process with a mock library, or spin up a real Redis instance via Testcontainers. Both approaches have distinct trade-offs that affect test speed, reliability, and the bugs you catch. This guide walks through both options in
Testing
Integration testing for microservices is where good intentions go to die.
TestContainers
Integration tests that mock database clients are better than no tests, but they create a gap: mock behavior diverges from real behavior.
Testing
MinIO is an S3-compatible object storage server you can run locally or in production. Testing it properly means running a real MinIO instance — TestContainers makes this easy in both Java and Python by spinning up a MinIO Docker container per test suite and tearing it down automatically. Key Takeaways
Database Testing
PostgreSQL is the world's most popular open-source relational database — and testing PostgreSQL-backed applications is one of the most important skills a backend engineer can have. This guide covers the full spectrum: fast in-memory tests with pg-mem, realistic integration tests with Testcontainers, and patterns that
gRPC
Unit tests are fast but incomplete — they mock dependencies that can behave differently in production.