Mutant (mutation testing)

Trust Score 95/100

from mutant2,118

Run Mutant mutation testing, analyze alive mutations, and produce clear fix actions (add tests or simplify code).

triggers:mutation testingmutantalive mutationmutation coveragerun mutantmutation report

GitHub SKILL.md

What it does

This skill guides an agent through running the Mutant mutation testing tool for Ruby projects, interpreting the output, and recommending concrete remediation steps. For each surviving (alive) mutation it prescribes either adding a targeted test or simplifying code, and it documents when a mutation is unkillable.

When to use it

Activate when you need to run mutation testing, respond to alive mutations reported by Mutant, or verify mutation coverage after changes. Useful in CI investigations, code quality reviews, and test-suite hardening efforts.

What's included

Scripts: none bundled, but usage commands and a checklist for running Mutant are provided.
References: none listed in SKILL.md.
Instructions: step-by-step guidance for running mutation tests, reading evil: lines, deciding between adding tests or simplifying code, and reporting format with BLUF verdicts. Also includes a checklist and prepare-legacy-project commands.

Compatible agents

Best for agents able to run Ruby tooling and read test suites (CI-capable agents or developer-focused agents like Copilot/Codex/Gemini CLI that can invoke shell commands and inspect repo files).

Audit Summary

Mutant is a well-crafted instructional skill for running Ruby mutation testing via the mutant gem. No bundled scripts — it's purely documentation/guidance. The SKILL.md is exceptionally detailed, covering output interpretation, fix strategies (add test vs simplify code), the principle of least power, and a structured reporting format. No security concerns whatsoever. Niche audience (Ruby devs doing mutation testing) but genuinely useful for that audience.

Watch Out

Ruby-specific — only useful for projects using the mutant gem
Requires bundler and mutant to be installed in the project

Notes

Very high-quality instructional skill. One of the better-written SKILL.md files — clear structure, excellent pedagogical content on mutation testing philosophy. No scripts to audit. Purely a guide skill.

Information

Repository: mutant
Stars: 2,118
Installs: 0

Trust Score

Overall95

Security100

Code Quality92

Architecture88

Usefulness55

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