Use when implementing any feature or bugfix and a test-driven approach is appropriate (red-green-refactor, seams-first), or when the user asks to find testing gaps, mutation test, or identify surviving mutants. Unit and integration tests only; browser journeys go to e2e-testing, test infrastructure to observability-quality, completion claims to gates.
Test scenarios, coverage analysis, test quality standards, and the mandatory test failure stop protocol. Load this skill for any task requiring test coverage.
Use when defining a test strategy, choosing layers, raising meaningful coverage, or fixing flaky suites — write tests with the feature, failing test first for bugs, QA audit before launch.
Write and review tests at all levels — Unit, Integration/Feature, and E2E — following Martin Fowler's testing pyramid. Use this skill when creating, modifying, or reviewing any test. Prevents test bloat, fragile assertions, and misplaced test levels. Adapts to any language/framework by following the decision flowchart and layer guidelines.
Use when writing, running, or fixing automated tests, including tests for new code, regression tests, one test or a whole suite, failing or flaky tests, snapshots and golden files, mocks, and coverage. Runs tests non-interactively, shows each new test can fail, keeps tests deterministic, and never deletes, skips, or weakens a test to get a green run.
Apply battle-tested strategies for unit, integration, and E2E testing in production SaaS applications. TRIGGER this skill automatically when the user mentions: writing tests, Jest, Vitest, Playwright, Cypress, test coverage, unit tests, integration tests, E2E tests, mocking, test setup, "how do I test this", TDD, testing hooks or components, testing API routes, CI test runs, or any quality assurance topic. Also trigger when new features are added without tests or when existing tests are failing unexpectedly.
Produce proportionate automated evidence for software behavior. Use when writing or selecting tests, checking a regression or requirement, investigating a test failure, or assessing whether passing tests support a claim. Compose with implementation, debugging, browser QA, and code review as needed; do not take over their workflows or require tests for every trivial reversible edit.
Testing strategy, coverage analysis, and quality assurance. Use when: (1) Planning test strategy for a story, (2) Analyzing test coverage, (3) Reviewing test quality in PRs, (4) Creating mocks for integrations, (5) Defining testing standards. Referenced by developer-analysis (test strategy in design) and git-workflow (PR review test verification).
How to test in this repo — the verification loop, the four unit-test archetypes, MSW mock handlers, and Playwright e2e. Use when writing or fixing any test, adding a mock endpoint, or deciding whether a change is adequately covered.
How to test a full-stack app to a shipping bar, distilled from a real recruiter-led SaaS. Covers the test layers (unit, integration, contract, end-to-end, smoke, regression, security, performance, accessibility), what to run per change versus per release, the cross-viewport visual discipline (mobile, tablet, desktop, wide), the "verify for real" principle that a passing type-check is not a passing feature, hermetic stubbed e2e, tenant-isolation as a standing regression gate, and the file-upload and authorization security checks that keep a multi-tenant app safe. Load when writing tests, setting up a test harness, deciding what to verify before a commit, or reviewing whether a change is actually safe to ship. Fetch current framework docs with Context7 rather than from memory.
Use when writing, modifying, running, or reviewing tests for the project. Covers what to test, what not to test, structure, naming, fixtures, coverage targets, and the rule that tests are written against behaviour — never modified to paper over broken code.
Test strategy, audit and writing - decides what is worth testing and at which level, audits an existing suite for tests that can't fail, flakiness and gaps in risky behaviour, or writes missing unit, integration and E2E tests that follow the project's conventions. Stack-agnostic.
A folder with a SKILL.md file: a name, a description of when to use it, and instructions. Claude loads a skill only when the task matches its description.
How do I use one I find here?
Copy the folder into your project's .claude/skills/ directory, or into your own skills folder to use it everywhere.
What do the warnings mean?
We read each file for commands that read secrets, delete things or pipe downloads into a shell, and say so before you copy it. No warning is not a promise that a file is safe.
Which skills worked for people?
Open a skill to see its discussion. Reports from people and their agents are coming.