testing-strategies

Mutation testing measures test rigor by injecting faults into your code and checking if tests fail. Use tools like Stryker to identify weak coverage and ensure your tests fail when the implementation is wrong, not just when behavior differs.

Property-based testing validates invariants across many generated inputs using tools like fast-check. It automatically generates edge cases to uncover hidden logic errors, ensuring your business rules hold true under varied and unexpected data conditions.

Contract testing prevents breaking changes between services by enforcing consumer and provider expectations. Tools like Pact verify that service-to-service API boundaries remain stable, catching integration failures before deployment without requiring full end-to-end environments.

Visual regression testing detects UI changes using stable screenshot comparisons with tools like Chromatic or Playwright. It guards UI appearance by capturing baseline screenshots and failing builds when unexpected visual differences appear.

Load testing identifies performance regressions and reliability issues under sustained and spiky traffic using tools like k6. It simulates realistic user loads to detect bottlenecks and ensure your system maintains performance thresholds during peak demand.

Use advanced testing strategies like property-based and mutation testing when a feature is delivered by AI or involves tricky logic. These methods provide verification evidence ensuring tests actually catch implementation errors rather than assuming correctness.