How does mutation testing differ from standard code coverage?

While code coverage measures which lines were executed, mutation testing measures whether your tests actually catch changes in logic. A high mutation score ensures your tests are effective, not just present.

Will running mutation tests slow down my CI/CD pipeline?

Mutation testing can be resource-heavy. This skill includes optimization strategies like incremental testing and targeting only critical modules to maintain speed.

Which programming languages and tools are supported?

This skill provides implementation patterns for major ecosystems, including JavaScript/TypeScript (Stryker), Python (mutmut), and Java (PITest).

What should I do when a mutant 'survives'?

A survived mutant indicates a gap in your tests. The skill helps you analyze the survivor to determine if you need to add a new boundary test or strengthen an existing assertion.

Mutation Testing Expert

Name: Mutation Testing Expert
Author: jmagly

byjmagly

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安全与测试

Validates test suite effectiveness by introducing intentional code defects to identify weak assertions and untested logic.

The Mutation Test skill empowers developers to go beyond simple code coverage metrics by measuring the actual effectiveness of their test suites. By systematically introducing 'mutants'—small changes in the source code like operator swaps or boundary shifts—it verifies if existing tests are capable of detecting these regressions. It provides detailed reports on mutation scores, identifies survived mutants, and offers specific recommendations for hardening tests in critical modules across JavaScript, Python, and Java environments, ensuring that high coverage actually translates to high quality.

主要功能

01Automated mutation testing setup for JavaScript, Python, and Java

02CI/CD integration patterns for automated quality gates

03Incremental testing support to analyze only changed code

04Comprehensive mutation score reporting and survivor analysis

0567 GitHub stars

06Identification of weak assertions in high-coverage codebases

使用场景

01Investigating why specific bugs escaped a comprehensive test suite

02Validating if high code coverage reflects actual test effectiveness

03Assessing test suite health and reliability before critical production releases

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add jmagly/ai-writing-guide mutation-test

For use in Claude.ai and ChatGPT

Download Skill