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mutation-testing

v3.9.0

Validate test effectiveness with mutation testing using Stryker (TypeScript/JavaScript) and mutmut (Python). Find weak tests that pass despite code mutations. Use to improve test quality.

CodexClaude Code1 Skill

By Claude Skills MaintainersLicense: MIT227 GitHub starsUpdated last week

Directory evidence

Runtimes
Codex and Claude Code
Parsed components
1 skill or MCP entry
Source updated
Sep 28, 2026
Manifest status
Canonical path parsed

The directory validates manifest shape and source location. It does not execute the plugin or provide a security endorsement. Review the indexing methodology →

Install mutation-testing for Codex and Claude Code

Installs for the current user
codex plugin marketplace add secondsky/claude-skills
codex plugin marketplace upgrade claude-skills
codex plugin add mutation-testing@claude-skills

Paste and run these commands in a terminal with Codex. They add and refresh the claude-skills catalog, then install this plugin.

Compatibility: the page URL and API slug “mutation-testing-3” remain stable.

  • Codex: mutation-testing-3@agent-plugin-marketplace → mutation-testing@claude-skills

The installer fetches third-party code from the source repository shown on this page. This directory validates manifest structure and source location, but does not perform a security audit; review the manifest, components, and source before installing.

Get the source manually
git clone https://github.com/secondsky/claude-skills

Clone the source repository, then follow its setup instructions to add the plugin to a compatible client. The plugin root is plugins/mutation-testing/.

Plugin files

plugins/mutation-testing/
├── .codex-plugin/plugin.json
├── .claude-plugin/plugin.json
└── skills/mutation-testing/SKILL.md

Included Skills1

mutation-testingskills/mutation-testing/SKILL.md

Validate test effectiveness with mutation testing using Stryker (TypeScript/JavaScript with Vitest or bun test via @hughescr/stryker-bun-runner) and mutmut (Python). Find weak tests that pass despite code mutations. Use to improve test quality.

Plugin manifests2

plugins/mutation-testing/.codex-plugin/plugin.json
{
  "name": "mutation-testing",
  "version": "3.9.0",
  "description": "Validate test effectiveness with mutation testing using Stryker (TypeScript/JavaScript) and mutmut (Python). Find weak tests that pass despite code mutations. Use to improve test quality.",
  "author": {
    "name": "Claude Skills Maintainers",
    "email": "[email protected]"
  },
  "license": "MIT",
  "repository": "https://github.com/secondsky/claude-skills",
  "keywords": [
    "mutation-testing",
    "mutation",
    "testing",
    "tests",
    "unit-tests",
    "quality"
  ],
  "skills": "./skills/",
  "interface": {
    "displayName": "Mutation Testing",
    "shortDescription": "Validate test effectiveness with mutation testing using Stryker",
    "longDescription": "Validate test effectiveness with mutation testing using Stryker (TypeScript/JavaScript) and mutmut (Python). Find weak tests that pass despite code mutations. Use to improve test quality.",
    "developerName": "Claude Skills Maintainers",
    "category": "Testing",
    "capabilities": [
      "Read",
      "Write"
    ],
    "defaultPrompt": [
      "Help me with Mutation Testing.",
      "Show me best practices for Mutation Testing.",
      "Guide me through using Mutation Testing effectively."
    ]
  }
}
plugins/mutation-testing/.claude-plugin/plugin.json
{
  "name": "mutation-testing",
  "description": "Validate test effectiveness with mutation testing using Stryker (TypeScript/JavaScript) and mutmut (Python). Find weak tests that pass despite code mutations. Use to improve test quality.",
  "version": "3.9.0",
  "author": {
    "name": "Claude Skills Maintainers",
    "email": "[email protected]"
  },
  "license": "MIT",
  "repository": "https://github.com/secondsky/claude-skills",
  "keywords": [
    "mutation-testing",
    "mutation",
    "testing",
    "tests",
    "unit-tests",
    "quality"
  ]
}

For maintainers

If you maintain this plugin, link to this source-backed listing from your README so users can review its manifest and indexed components.

[mutation-testing on Agent Plugins Marketplace](https://pluginsmp.com/plugins/mutation-testing-3)