Testing

How to test database migrations in CI with production-shaped data, compatibility checks, backfill verification, schema drift detection, and rollback gates.

How to diagnose flaky integration tests in CI: shared state, timing assumptions, parallel worker conflicts, database cleanup gaps, and unstable dependencies.

How API contract testing catches breaking request, response, and schema changes before release with OpenAPI diffs, consumer examples, and CI checks.

A practical guide to API integration testing: real request boundaries, auth, persistence checks, failure cases, idempotency, and response contracts.

Tests can pass while production still breaks when the suite proves the intended path but misses retries, concurrency, dirty data, and rollout state.