QA & Test Automation

Builds realistic domain fixtures, factories, and edge-case datasets with the builder pattern and valid defaults. Use when a test needs domain objects, seed data, factories, or boundary/edge-case inputs; do NOT use when a test needs to fake a network call, database, clock, or third-party SDK — use mock-stub-designer instead.

Write consumer-driven contract tests at service and API boundaries so an incompatible change fails a build instead of breaking integrations silently in production. Use when a client and a service (or two services) must stay in sync across separate deploys — adding a Pact consumer test, replaying a pact file in provider verification, publishing pacts to a Pact Broker / PactFlow, gating with can-i-deploy, or after a renamed field or changed status code broke a consumer that unit tests passed.

Converts an acceptance criterion or user story into one maintainable Playwright or Cypress end-to-end test that reads like the journey it covers. Use when turning a Given/When/Then acceptance criterion or user story into a browser test, when asked to "write an E2E test for this AC", or when a feature's critical journey (login, checkout, signup) needs a single automated scenario. Do NOT use when writing general Playwright tests, configuring the runner, or fixing existing test flakiness — use playwright-testing or flaky-test-detangler instead.

Designs the minimal set of test doubles for a unit or integration test and decides, per dependency, what to fake versus exercise for real. Use when a test touches an external boundary — an HTTP/third-party API, payment or email/SMS SDK, the database, the filesystem, the system clock, or randomness — or when existing tests over-mock and pass while the system is broken.

Runs mutation testing on already-covered code and turns each surviving mutant into a specific missing assertion, exposing tests that execute code but verify nothing. Use when line coverage is high yet a bug slipped through, when reviewing a critical module (pricing, permissions, auth, state machines) before release, or when you are asked to run Stryker, PIT, mutmut, or cosmic-ray. Do NOT use when the goal is to find which code paths are untested at all — use coverage-gap-finder instead.

Reliable end-to-end browser tests with resilient selectors and no flaky waits.

Enforces Red-Green-Refactor discipline: write the failing test first, then the minimum code to pass it.