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mutation-testing

Apply behavioral mutations to validate test suite regression detection.

4|Updated Jun 1, 2026
Search Tags:#code review#quality gates#mutation testing#regression detection#test effectiveness#ci validation#assertion coverage
One-click install
npx skills add https://github.com/vmobifystudio/app-dev-team --skill mutation-testing-vmobifystudio
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: mutation-testing
Source: https://github.com/vmobifystudio/app-dev-team/tree/main/skills/mutation-testing
Command: npx skills add https://github.com/vmobifystudio/app-dev-team --skill mutation-testing-vmobifystudio

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill exposes green test suites that fail to detect meaningful regressions by deliberately breaking gates, assertions, hooks, and verification rules, helping you identify ineffective coverage before changes ship.

Core Features & Use Cases

  • Automated Mutation Runs: Apply catalogued behavioral mutations in an isolated temporary copy and report whether the test suite catches each one.
  • Assertion Validation: Distinguish mutations caught by the intended assertion from those detected only by unrelated checks.
  • Safe Iteration: Run the complete catalog, list available mutations, sample mutations for pull requests, or target one mutation while developing a new gate.
  • Use Case: After adding a guard to a verification script, run the targeted mutation to confirm that the guard's own named test assertion fails when the behavior is inverted.

Quick Start

Run the mutation-testing skill against the repository's test suite and report all caught, surviving, excluded, and untestable mutations.

Frequently Asked Questions about mutation-testing

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How can I tell if my test suite has effective assertion coverage or if a green build is misleading?▼

Mutation testing validates assertion coverage by deliberately breaking guard rules, hooks, and gates to expose green test suites that fail to catch meaningful regressions before changes ship.

How do I verify that a new CI validation guard actually detects regressions?▼

To verify CI validation guards, apply targeted behavioral mutations to the repository script and confirm the guard's named test assertion fails when the behavior is inverted.

Do I need an executable mutation runner to perform regression detection on repository scripts?▼

Yes, regression detection requires an executable mutation runner, catalogued mutation anchors, a baseline-green test suite, and isolated repository state protection to safely apply behavioral mutations.

Can I sample specific behavioral mutations for a pull request instead of running the full test effectiveness catalog?▼

Yes, you can sample specific behavioral mutations for pull requests, run the complete catalog, list available mutations, or target one mutation while developing a new gate.

What is the best way to distinguish mutations caught by intended assertions from unrelated checks?▼

Assertion validation distinguishes mutations caught by intended assertions from those detected by unrelated checks by applying deliberate behavioral mutations in an isolated temporary copy.

How does mutation testing protect my repository state when applying deliberate behavioral mutations?▼

Mutation testing protects repository state by applying deliberate behavioral mutations in an isolated temporary copy, ensuring the original repository remains safe while reporting surviving mutations.

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