Stage 3 · Build
Testing & Release Confidence
Integration Testcontainers
Run PostgreSQL, Redis, and NATS dependencies in Testcontainers with migrations and cleanup hooks.
8 min readBuilding Backend ApplicationsBuild
Why Testcontainers
Integration tests need real databases. Testcontainers spins up Docker containers for PostgreSQL, Redis, and other services. Tests run against real infrastructure without polluting shared environments.
Setup PostgreSQL
Gopostgresql-testcontainer.go
47 linesLn 1, Col 1Go
GenericContainer starts a PostgreSQL Docker container. MappedPort gets the dynamically assigned port. t.Cleanup ensures the container is terminated after tests.
Setup Redis
Goredis-testcontainer.go
32 linesLn 1, Col 1Go
Redis Testcontainer follows the same pattern. Start the container, create the client, register cleanup. Each test gets a fresh Redis instance.
Migrations in Tests
Gorunning-migrations-in-tests.go
36 linesLn 1, Col 1Go
Run migrations against the test database. Seed fixtures after migrations. Use ON CONFLICT DO NOTHING for idempotent seeding.
Cleanup Hooks
Gotest-cleanup-patterns.go
17 linesLn 1, Col 1Go
t.Cleanup runs after the test completes. Truncate tables to reset state. This ensures tests do not interfere with each other.
Parallel Tests
Goparallel-integration-tests.go
16 linesLn 1, Col 1Go
t.Parallel() runs subtests concurrently. Each test gets its own database connection. This speeds up test suites significantly.
Use docker-compose for CI
In CI, use docker-compose to start PostgreSQL and Redis before tests. This is faster than Testcontainers for CI pipelines. Use Testcontainers for local development.
Mark this lesson complete to store local progress and unlock a cleaner resume path the next time you visit.