How do you write integration tests for a Go service that depends on a PostgreSQL database?

Use testcontainers-go to spin up a real Postgres container per test suite, run migrations, and wrap each test in a transaction that is rolled back at the end for isolation.

Integration test with testcontainers

Integration test strategy

1
Build tag //go:build integration keeps integration tests separate from unit tests
2
Transaction rollback per test ensures test isolation without truncating tables
3
TestMain sets up the container once per test suite — not per test case
4
Pass tx (implementing DBTX interface) to the repository — works transparently
5
Run in CI with: go test -tags=integration ./...