Testing Skills
A curated collection of 7 testing skills for building with AI coding agents.
Contract Test Designer
Design consumer-driven contract tests between services so an API provider can't break its consumers unnoticed — without slow, flaky full end-to-end environments. Use when independent services or teams integrate over an API, when integration bugs only surface in staging or prod, or when E2E suites are too slow and brittle to catch breaking API changes.
Coverage Gap Finder
Run the project's coverage tool and identify the highest-value untested paths — error branches, edge cases, and critical modules — then propose specific test cases for each gap. Use when you have a coverage report but don't know where new tests will pay off most.
Integration Test Designer
Design integration tests that exercise components against REAL collaborators — actual database, queue, HTTP boundary — at a deliberately chosen seam, instead of a unit suite that mocks everything or a slow flaky full E2E. Use when bugs slip past green unit tests, when wiring or contracts between layers break in production, or when a mocked DB test passes but the real query/migration/serialization fails.
Mock Data Factory
Generate a typed mock/fixture factory for a given type, interface, or schema, inferring believable values from field names and types. Use when tests or local dev need realistic, type-safe sample data with per-field overrides.
Mutation Test Runner
Measure whether a test suite actually catches bugs by running mutation testing — introduce small faults into the code and check which ones a test kills versus which slip through silently. Use when line coverage is high but bugs still ship, when you suspect tests assert weakly, or to find the exact assertions a suite is missing.
Property Test Designer
Design property-based tests — generate hundreds of random inputs and assert invariants that must hold for ALL of them — to surface the edge cases hand-picked examples never reach. Use when code has a large input space (parsers, serializers, encoders, math, data transforms), when a bug keeps slipping through despite green example tests, or when you can't enumerate every case worth checking.
Test Scaffolder
Scaffold a test file with sensible cases for a given module or function. Use when adding tests to untested code and you want a fast, structured starting point.