Which languages and tools does this skill support?

This skill provides specialized knowledge for TypeScript and JavaScript using Stryker Mutator, and Python using the mutmut library.

How does mutation testing differ from standard code coverage?

Code coverage only measures which lines of code were executed during a test. Mutation testing measures the effectiveness of the assertions by checking if the tests actually notice when logic is changed.

Will mutation testing slow down my development workflow?

It can be resource-intensive, but this skill provides strategies for incremental testing, targeting specific files, and optimizing concurrency to maintain fast feedback loops.

What is mutation testing?

Mutation testing involves making small, deliberate changes to your source code (mutants) and running your tests; if the tests still pass, it indicates the test suite is weak and failed to catch the 'bug' introduced by the mutation.

What is a good mutation score to aim for?

A mutation score of 80% or higher is generally considered excellent, indicating that the vast majority of potential logic errors are caught by your current test suite.

Mutation Testing Expert

Name: Mutation Testing Expert
Author: laurigates

bylaurigates

•

セキュリティとテスト

Validates test suite effectiveness by introducing deliberate code mutations to identify weak assertions and untested logic paths.

This skill empowers developers to go beyond simple code coverage by performing mutation analysis using industry-standard tools like Stryker for TypeScript/JavaScript and mutmut for Python. It provides expert guidance on identifying 'survived' mutants—code changes that tests fail to catch—thereby revealing gaps in test logic, weak assertions, and dead code. By integrating mutation testing into your workflow, you can ensure that your test suite truly verifies application behavior rather than just executing lines of code, leading to significantly higher software reliability and confidence.

主な機能

01Comprehensive guidance for Stryker and mutmut configuration and setup

02Cross-language support for TypeScript, JavaScript, and Python environments

03Expert interpretation of mutation scores and automated reporting workflows

043 GitHub stars

05In-depth analysis of survived mutants to identify weak or missing assertions

06Incremental testing strategies to optimize performance in CI/CD pipelines

ユースケース

01Integrating automated mutation score thresholds into GitHub Actions to maintain code quality

02Hardening critical business logic modules by ensuring every logic branch is meaningfully tested

03Auditing existing test suites to find 'fake' coverage where tests pass but don't assert behavior

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add laurigates/claude-plugins mutation-testing

For use in Claude.ai and ChatGPT

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