Validates test suite effectiveness by introducing deliberate code mutations to identify and fix weak test cases.
This skill empowers Claude to go beyond simple code coverage by performing mutation testing using Stryker for TypeScript/JavaScript and mutmut for Python. It works by injecting small, intentional faults into your source code—if your tests still pass, they are marked as 'survived,' indicating a gap in your test logic. This is an essential tool for developers building high-reliability systems who need to ensure their test suites actually catch bugs rather than just executing lines of code.
主な機能
01Guidance on fixing common test smells and boundary condition gaps
02Automated mutation analysis for TypeScript/JS (Stryker) and Python (mutmut)
0321 GitHub stars
04Support for incremental testing to focus only on changed files
05Detailed HTML report generation and interpretation
06Identification of 'survived' mutants to pinpoint weak assertions
ユースケース
01Setting quality gates in CI/CD pipelines based on mutation scores
02Improving reliability for mission-critical business logic and edge cases
03Auditing existing test suites to find tests that pass even when logic is broken
