How do I install the Mutation Testing skill?

Run npx skillmds@latest add amplicode/mutation-testing in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Mutation Testing safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Mutation Testing?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Mutation Testing free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Mutation Testing?

amplicode (@amplicode) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Mutation Testing by amplicode — Agent Skill

Name: Mutation Testing
Author: amplicode

Mutation Testing

Set up and run mutation testing with PIT (pitest) on a Gradle project, and read the mutation score. Use this skill whenever the user wants mutation testing added to a build, configured, run or re-run, wants a mutation score or a mutation report interpreted, asks why a particular mutant survived, or asks what should be excluded from mutation analysis, or wants something added to those exclusions — in any language, and whether or not the tool is named. Also use it when the task calls for it: checking test quality rather than coverage — a high JaCoCo number can hide tests that assert nothing.

amplicode 0b9bcee 8 files · 33.0 KB Updated Sep 17, 2026

File contents

Mutation testing

Steps

Start by reading this skill's own pitest entry for THIS project (type: project) — the checks below are built on it. A missing entry is not an error; it means nothing has been recorded yet.

Then work through the steps in order. Each carries a check: when the check fires the step is already done — skip it and move on. Load a step's reference only if you actually run that step, so there is context left for the PIT output.

1. Configure PIT in the build

Skip if PIT is already configured. Two signals say so — stop at the first hit:

The entry describes a configuration for this project. That is enough: skip the step, and do not spend a command confirming what the entry just said.

No entry — then ask the build file:

grep -n "info.solidsoft.pitest" build.gradle build.gradle.kts 2>/dev/null

Otherwise follow references/configuration.md, which applies the exclusions as part of the setup.

If step 3 then fails with Task 'pitest' not found, the entry was stale: say so, run this step after all, and continue.

2. Adjust what gets mutated

Skip if the request has nothing to do with the exclusions or targetClasses.

Otherwise follow references/add-exclusion.md. It answers a question as well as it applies a change — when the request is only a question, stop after judging the candidate and leave the build alone.

3. Run PIT and report the score

Skip if the user asked only to wire PIT into the build, or only for advice on what to exclude — then say a run is available and stop there.

Otherwise follow references/usage.md.

4. Record what was resolved

Skip if the entry already describes what the run actually used.

Otherwise write or update pitest in the shape references/configuration.md step 5 defines. This is what lets step 1 be skipped next time, so it is not optional bookkeeping — dropping it makes the next run pay for the version probing and compatibility checks all over again.

---name: mutation-testingdescription: Set up and run mutation testing with PIT (pitest) on a Gradle project, and read the mutation score. Use this skill whenever the user wants mutation testing added to a build, configured, run or re-run, wants a mutation score or a mutation report interpreted, asks why a particular mutant survived, or asks what should be excluded from mutation analysis, or wants something added to those exclusions — in any language, and whether or not the tool is named. Also use it when the task calls for it: checking test quality rather than coverage — a high JaCoCo number can hide tests that assert nothing.---# Mutation testing## StepsStart by reading this skill's own `pitest` entry for THIS project(`type: project`) — the checks below are built on it. A missing entry is not anerror; it means nothing has been recorded yet.Then work through the steps in order. Each carries a check: when the check firesthe step is already done — skip it and move on. Load a step's reference only ifyou actually run that step, so there is context left for the PIT output.### 1. Configure PIT in the build**Skip if** PIT is already configured. Two signals say so — stop at the first hit:- **The entry** describes a configuration for this project. That is enough: skip the step, and do not spend a command confirming what the entry just said.- **No entry** — then ask the build file: ```bash grep -n "info.solidsoft.pitest" build.gradle build.gradle.kts 2>/dev/null ```Otherwise follow `references/configuration.md`, which applies the exclusions aspart of the setup.If step 3 then fails with `Task 'pitest' not found`, the entry was stale: say so,run this step after all, and continue.### 2. Adjust what gets mutated**Skip if** the request has nothing to do with the exclusions or `targetClasses`.Otherwise follow `references/add-exclusion.md`. It answers a question as well asit applies a change — when the request is only a question, stop after judging thecandidate and leave the build alone.### 3. Run PIT and report the score**Skip if** the user asked only to wire PIT into the build, or only for advice onwhat to exclude — then say a run is available and stop there.Otherwise follow `references/usage.md`.### 4. Record what was resolved**Skip if** the entry already describes what the run actually used.Otherwise write or update `pitest` in the shape `references/configuration.md`step 5 defines. This is what lets step 1 be skipped next time, so it is notoptional bookkeeping — dropping it makes the next run pay for the version probingand compatibility checks all over again.

Frequently asked questions