Set up and run mutation testing with Stryker, including full-project and focused diff runs against the current review base, then use surviving mutants to strengthen weak or missing tests.
$ npx skills add citypaul/.dotfiles --skill mutation-testing -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install citypaul/.dotfiles mutation-testing --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/citypaul/.dotfiles.git skills-src && mkdir -p .claude/skills && cp -r skills-src/claude/.claude/skills/mutation-testing .claude/skills/mutation-testing && rm -rf skills-srcUse ~/.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/
Install the "mutation-testing" agent skill from https://github.com/citypaul/.dotfiles/tree/main/claude/.claude/skills/mutation-testing into .claude/skills/mutation-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mutation-testing", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/citypaul/.dotfiles/tree/main/claude/.claude/skills/mutation-testingType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add citypaul/.dotfiles --skill mutation-testing -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install citypaul/.dotfiles mutation-testing --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/citypaul/.dotfiles.git skills-src && mkdir -p .agents/skills && cp -r skills-src/claude/.claude/skills/mutation-testing .agents/skills/mutation-testing && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "mutation-testing" agent skill from https://github.com/citypaul/.dotfiles/tree/main/claude/.claude/skills/mutation-testing into .agents/skills/mutation-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mutation-testing", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add citypaul/.dotfiles --skill mutation-testing -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install citypaul/.dotfiles mutation-testing --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/citypaul/.dotfiles.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/claude/.claude/skills/mutation-testing .cursor/skills/mutation-testing && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "mutation-testing" agent skill from https://github.com/citypaul/.dotfiles/tree/main/claude/.claude/skills/mutation-testing into .cursor/skills/mutation-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mutation-testing", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/citypaul/.dotfiles.git --path claude/.claude/skills/mutation-testing--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add citypaul/.dotfiles --skill mutation-testing -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install citypaul/.dotfiles mutation-testing --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/citypaul/.dotfiles.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/claude/.claude/skills/mutation-testing .gemini/skills/mutation-testing && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "mutation-testing" agent skill from https://github.com/citypaul/.dotfiles/tree/main/claude/.claude/skills/mutation-testing into .gemini/skills/mutation-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mutation-testing", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install citypaul/.dotfiles mutation-testingInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add citypaul/.dotfiles --skill mutation-testing -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/citypaul/.dotfiles.git skills-src && mkdir -p .github/skills && cp -r skills-src/claude/.claude/skills/mutation-testing .github/skills/mutation-testing && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "mutation-testing" agent skill from https://github.com/citypaul/.dotfiles/tree/main/claude/.claude/skills/mutation-testing into .github/skills/mutation-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mutation-testing", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add citypaul/.dotfiles --skill mutation-testing -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install citypaul/.dotfiles mutation-testing --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/citypaul/.dotfiles.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/claude/.claude/skills/mutation-testing .opencode/skills/mutation-testing && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "mutation-testing" agent skill from https://github.com/citypaul/.dotfiles/tree/main/claude/.claude/skills/mutation-testing into .opencode/skills/mutation-testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mutation-testing", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
mutation-testingSet up and run mutation testing with Stryker, including full-project and focused diff runs against the current review base, then use surviving mutants to strengthen weak or missing tests.
Mutation Testing is an agent skill from citypaul/.dotfiles. Set up and run mutation testing with Stryker, including full-project and focused diff runs against the current review base, then use surviving mutants to strengthen weak or missing tests. Use as the end-of-phase PR-readiness gate after implementation and refactoring are complete, not inside each RED-GREEN increment. Also use when the user explicitly asks for mutation testing, Stryker, mutation score, or surviving-mutant analysis. For writing the tests themselves, see testing.
Its SKILL.md is about 4k tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files (for example `resources/mutator-rules.md`).
It sits in Testing & QA, covering Test coverage and Refactoring.
5 steps, taken from the step headings in SKILL.md.
Read from SKILL.md and the folder at commit cd4028d. It shows what the files ask for, not the result of running them.
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.
Shell commands in SKILL.md call:
gitrgpnpmFrom the folder's file list and the shell code blocks in SKILL.md.
No URLs in SKILL.md. Its commands use git and pnpm, which can reach the network depending on how they are called.
From URLs in SKILL.md, links to its own repository left out.
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Mutation Testing loads about 4k tokens when it runs. Until then it costs about 124 tokens; SKILL.md has 2,024 words of instructions outside code blocks.
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.
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.
Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 2,024 words (~4,036 tokens).
“For writing good tests (factories, behavior-driven patterns), load the testing skill. This skill focuses on verifying test effectiveness.”
SKILL.md and 1 other file in claude/.claude/skills/mutation-testing of citypaul/.dotfiles.
Open the folder on GitHubat commit cd4028d
Mutation Testing 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.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Mutation Testing this skillcitypaul/.dotfiles | 739 | — | ~4k | Automated safety check: Pass | Custom licence | |
| Memstack Development Test Writercwinvestments/memstack | 423 | — | ~3.7k | Automated safety check: Pass | Proprietary | |
| Skillshare Codebase AuditJetBrains/skills | 364 | 1 repos | ~1.9k | Automated safety check: Pass | None | |
| Test Guidelinesgetsentry/sentry-dart | 873 | — | ~3.1k | Automated safety check: Pass | MIT | |
| Test Coveragescott-fryxell/brayness | 124 | — | ~1.6k | Automated safety check: Pass | MIT | |
| TDD ImplementFastLED/FastLED | 7.5k | — | ~1k | Automated safety check: Pass | MIT |
cwinvestments/memstack
A skill your agent uses when the user says 'write tests', 'add tests', 'test coverage', 'unit tests', 'integration tests', 'component tests', 'mocking', 'edge cases', or needs to generate tests with…
JetBrains/skills
Cross-validate CLI flags, docs, tests, and targets for consistency across the codebase.
getsentry/sentry-dart
Enforce Sentry Dart/Flutter SDK test conventions for naming, structure, and fixtures.
scott-fryxell/brayness
Write Vitest specs for Vue 3 JavaScript (Vite Plus, happy-dom, @vue/test-utils) and analyze V8 coverage + Fallow health to prioritize test-first refactors.
FastLED/FastLED
Implement a feature or fix a bug using strict TDD. An agent skill from FastLED/FastLED.
bikeindex/bike_index
Bike Index's RSpec testing conventions — how to structure specs with context and let, what kinds of tests to write, and what to avoid (mocks, controller specs, testing private methods).
citypaul/.dotfiles
Discover and, with authorization, install agent skills from the open skills ecosystem.
citypaul/.dotfiles
Render the shape of code — module boundaries, the types that cross them, signatures, and a cited call graph — for code that already exists or a change about to be built.
citypaul/.dotfiles
Design, audit, and evolve physical source and package structures that expose real architectural boundaries while keeping related behavior together.
citypaul/.dotfiles
Review test quality using Dave Farley's eight properties of good tests.
citypaul/.dotfiles
A skill your agent uses when modifying existing code that lacks tests and you need to document its actual current behavior before making changes -- the legacy code dilemma where you need tests to…
citypaul/.dotfiles
Systematic CI/CD failure diagnosis using hypothesis-first investigation, local reproduction, and environment delta analysis.
Categories
Set up and run mutation testing with Stryker, including full-project and focused diff runs against the current review base, then use surviving mutants to strengthen weak or missing tests. dotfiles. Set up and run mutation testing with Stryker, including full-project and focused diff runs against the current review base, then use surviving mutants to strengthen weak or missing tests.
Mutation Testing fits situations like: the user explicitly asks for mutation testing; surviving-mutant analysis.
Run `npx skills add citypaul/.dotfiles --skill mutation-testing -a claude-code`. Or copy the skill folder (claude/.claude/skills/mutation-testing in citypaul/.dotfiles) into .claude/skills/mutation-testing in your project. Claude Code loads it when a task matches its description.
Run `npx skills add citypaul/.dotfiles --skill mutation-testing -a codex`. Or copy the skill folder (claude/.claude/skills/mutation-testing in citypaul/.dotfiles) into .agents/skills/mutation-testing in your project. Codex loads it when a task matches its description.
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add citypaul/.dotfiles --skill mutation-testing -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-testing, .gemini/skills/mutation-testing, .github/skills/mutation-testing and .opencode/skills/mutation-testing in your project.
Going by SKILL.md and its folder, Mutation Testing needs the command-line tools its instructions call (git, rg and pnpm).
SKILL.md contains no URLs. Its commands use git, which can reach the network depending on how they are called. This is read from the text; nothing was executed.
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.
Mutation Testing has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.
About 4k tokens (SKILL.md is roughly 16k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
Skills that share tags, products or a category with Mutation Testing: Memstack Development Test Writer (cwinvestments/memstack, 423 stars), Skillshare Codebase Audit (JetBrains/skills, 364 stars), Test Guidelines (getsentry/sentry-dart, 873 stars) and Test Coverage (scott-fryxell/brayness, 124 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
citypaul (a GitHub user) maintains it in citypaul/.dotfiles, which has 739 GitHub stars. The repository holds 44 skills in this directory. The repository was last updated on October 2, 2026.
Source: citypaul/.dotfiles on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.
