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Agent skill

Mutation Test Suite Optimizer

by ArabelaTso in ArabelaTso/Skills-4-SE

Optimize test suites using mutation testing to maximize mutation kill rate with minimal tests.

Apache-2.0Auto-check passedTesting & QA

Install Mutation Test Suite Optimizer

skills CLI
$ npx skills add ArabelaTso/Skills-4-SE --skill mutation-test-suite-optimizer -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install ArabelaTso/Skills-4-SE mutation-test-suite-optimizer --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/ArabelaTso/Skills-4-SE.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/mutation-test-suite-optimizer .claude/skills/mutation-test-suite-optimizer && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
mutation-test-suite-optimizer
GitHub stars
253
Token cost
~711 tokens
SKILL.md length
195 words
Files
1
Skills in repo
150
Repo updated
First seen
Licence
Apache-2.0

At a glance

Optimize test suites using mutation testing to maximize mutation kill rate with minimal tests.

  • Works in 5 steps: Test Selection - Identify minimal test… → Redundancy Removal - Eliminate tests… → Mutation Coverage - Maximize mutants… → …
  • You need to reduce test suite size while maintaining quality
  • SKILL.md covers Overview, Quick Start, What Gets Optimized and Mutation Operators, plus 3 more sections
  • Calls python

What it does

Mutation Test Suite Optimizer is an agent skill from ArabelaTso/Skills-4-SE. Optimize test suites using mutation testing to maximize mutation kill rate with minimal tests. Use when you need to reduce test suite size while maintaining quality, identify redundant tests, improve mutation coverage, or validate test effectiveness. The skill analyzes test coverage, execution intervals, and redundancy using mutation operators, selects or generates a minimal subset of tests that maximizes mutation kill rate, and outputs an optimized test suite with detailed reports showing killed and surviving…

Its SKILL.md is about 710 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Testing & QA, covering Test generation and Test coverage. The repository describes itself as: A curated list of 180+ useful Claude Skills for Software Engineering and resources for customizing AI for SE workflows. The licence is Apache-2.0.

When your agent uses it

  • You need to reduce test suite size while maintaining quality
  • Identify redundant tests
  • Improve mutation coverage
  • Validate test effectiveness

Example prompts

  • “/mutation-test-suite-optimizer”

Requirements

  • Python 3

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Test Selection - Identify minimal test subset for maximum coverage
  2. Redundancy Removal - Eliminate tests that kill same mutants
  3. Mutation Coverage - Maximize mutants killed
  4. Execution Time - Reduce overall test execution time
  5. Test Quality - Identify weak or ineffective tests

What it can do on your machine

Read from SKILL.md and the folder at commit 4f38503. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • python

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Mutation Test Suite Optimizer loads about 711 tokens when it runs. Until then it costs about 157 tokens; SKILL.md has 195 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~157
When it runs · the whole SKILL.md, loaded when a task matches
~711

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from ArabelaTso/Skills-4-SE at commit 4f38503, republished under its Apache-2.0 licence (© ArabelaTso). 195 words, ~711 tokens.

Download SKILL.mdSave it as .claude/skills/mutation-test-suite-optimizer/SKILL.md (or your agent's skills folder).
name
mutation-test-suite-optimizer
description
Optimize test suites using mutation testing to maximize mutation kill rate with minimal tests. Use when you need to reduce test suite size while maintaining quality, identify redundant tests, improve mutation coverage, or validate test effectiveness. The skill analyzes test coverage, execution intervals, and redundancy using mutation operators, selects or generates a minimal subset of tests that maximizes mutation kill rate, and outputs an optimized test suite with detailed reports showing killed and surviving mutants. Supports multiple programming languages and mutation testing frameworks.

Mutation Test Suite Optimizer

Overview

This skill optimizes test suites using mutation testing, selecting a minimal subset of tests that maximizes mutation kill rate while reducing execution time and redundancy.

Quick Start

bash
# Optimize test suite with mutation testing
python scripts/optimize.py /path/to/repo --tests tests/

# Use specific mutation operators
python scripts/optimize.py repo/ --tests tests/ --operators AOR,ROR,COR

# Generate optimization report
python scripts/optimize.py repo/ --tests tests/ --output report.json

What Gets Optimized

  1. Test Selection - Identify minimal test subset for maximum coverage
  2. Redundancy Removal - Eliminate tests that kill same mutants
  3. Mutation Coverage - Maximize mutants killed
  4. Execution Time - Reduce overall test execution time
  5. Test Quality - Identify weak or ineffective tests

Mutation Operators

Supports common mutation operators:

  • AOR - Arithmetic Operator Replacement
  • ROR - Relational Operator Replacement
  • COR - Conditional Operator Replacement
  • SOR - Shift Operator Replacement
  • LOR - Logical Operator Replacement
  • ASR - Assignment Operator Replacement

Optimization Report

Generates detailed report with:

  • Optimized Test Suite - Minimal test subset
  • Mutation Kill Rate - Percentage of mutants killed
  • Killed Mutants - List of detected mutants
  • Surviving Mutants - Mutants that escaped detection
  • Redundant Tests - Tests that can be removed
  • Execution Time Savings - Time reduction achieved

Example report:

json
{
  "original_tests": 150,
  "optimized_tests": 45,
  "mutation_kill_rate": 92.5,
  "killed_mutants": 185,
  "surviving_mutants": 15,
  "time_savings": "67%"
}

Usage

bash
python scripts/optimize.py <repo_path> --tests <test_dir> [--operators <ops>] [--output <report.json>]

Tips

  • Run regularly to maintain test suite quality
  • Focus on high-value tests that kill unique mutants
  • Remove redundant tests to speed up CI/CD
  • Use surviving mutants to guide new test creation
  • Balance mutation score with execution time
  • Integrate into continuous testing pipeline

© ArabelaTso, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/mutation-test-suite-optimizer of ArabelaTso/Skills-4-SE.

Open the folder on GitHubat commit 4f38503

Compare with similar skills

Mutation Test Suite Optimizer next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Mutation Test Suite Optimizer compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Mutation Test Suite Optimizer this skillArabelaTso/Skills-4-SE253—~711Automated safety check: PassApache-2.0
E2E Test ThinkerUniClipboard/UniClipboard1.9k—~1.7kAutomated safety check: PassAGPL-3.0
Ralph Coveragejvm-skills/jvm-skills140—~683Automated safety check: PassApache-2.0
Designing TestsCloudAI-X/opencode-workflow275—~2.9kAutomated safety check: PassMIT
Mutation Testingproffesor-for-testing/agentic-qe494—~1.7kAutomated safety check: PassMIT
Write Testsgnomeria/usbtree690—~622Automated safety check: PassMIT

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  • E2E Test Thinker

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Categories

Questions about Mutation Test Suite Optimizer

What does Mutation Test Suite Optimizer do?

Optimize test suites using mutation testing to maximize mutation kill rate with minimal tests. Mutation Test Suite Optimizer is an agent skill from ArabelaTso/Skills-4-SE. Optimize test suites using mutation testing to maximize mutation kill rate with minimal tests.

When should I use Mutation Test Suite Optimizer?

Mutation Test Suite Optimizer fits situations like: you need to reduce test suite size while maintaining quality; identify redundant tests; improve mutation coverage; validate test effectiveness.

How do I install Mutation Test Suite Optimizer in Claude Code?

Run `npx skills add ArabelaTso/Skills-4-SE --skill mutation-test-suite-optimizer -a claude-code`. Or copy the skill folder (skills/mutation-test-suite-optimizer in ArabelaTso/Skills-4-SE) into .claude/skills/mutation-test-suite-optimizer in your project. Claude Code loads it when a task matches its description.

How do I install Mutation Test Suite Optimizer in Codex?

Run `npx skills add ArabelaTso/Skills-4-SE --skill mutation-test-suite-optimizer -a codex`. Or copy the skill folder (skills/mutation-test-suite-optimizer in ArabelaTso/Skills-4-SE) into .agents/skills/mutation-test-suite-optimizer in your project. Codex loads it when a task matches its description.

Can I use Mutation Test Suite Optimizer in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add ArabelaTso/Skills-4-SE --skill mutation-test-suite-optimizer -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/mutation-test-suite-optimizer, .gemini/skills/mutation-test-suite-optimizer, .github/skills/mutation-test-suite-optimizer and .opencode/skills/mutation-test-suite-optimizer in your project.

What does Mutation Test Suite Optimizer need to run?

Going by SKILL.md and its folder, Mutation Test Suite Optimizer needs the command-line tools its instructions call (python). Our summary lists: Python 3.

Does Mutation Test Suite Optimizer access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Mutation Test Suite Optimizer safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Mutation Test Suite Optimizer use?

Mutation Test Suite Optimizer is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Mutation Test Suite Optimizer use?

About 711 tokens (SKILL.md is roughly 2.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Mutation Test Suite Optimizer?

Skills that share tags, products or a category with Mutation Test Suite Optimizer: E2E Test Thinker (UniClipboard/UniClipboard, 1.9k stars), Ralph Coverage (jvm-skills/jvm-skills, 140 stars), Designing Tests (CloudAI-X/opencode-workflow, 275 stars) and Mutation Testing (proffesor-for-testing/agentic-qe, 494 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Mutation Test Suite Optimizer?

ArabelaTso (a GitHub user) maintains it in ArabelaTso/Skills-4-SE, which has 253 GitHub stars. The repository holds 150 skills in this directory. The repository was last updated on August 21, 2026.

Source: ArabelaTso/Skills-4-SE on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.