mutation-testing

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.

1.43x

Quality

66%

Does it follow best practices?

Impact

93%

1.43x

Average score across 3 eval scenarios

Securityby

Passed

No findings from the security scan

Fix and improve this skill with Tessl

tessl review fix ./plugins/mutation-testing/skills/mutation-testing/SKILL.md

Evaluation results

100%

66%

Add Mutation Testing to a Bun-Native Test Suite

Bun native test runner stryker config

Criteria

Baseline

With context

Correct bun runner package

100%

Core package version

100%

Bun version requirement

100%

Config filename

100%

testRunner bun

100%

coverageAnalysis perTest

100%

Correct thresholds

100%

incremental enabled

100%

bun inspectorTimeout

100%

mutate pattern

100%

bunx stryker run command

100%

Improve Python Test Quality Using Mutation Testing

Python mutmut workflow and weak test improvement

Criteria

Baseline

With context

mutmut install via uv

100%

uv run mutmut run

100%

uv run mutmut results

100%

uv run mutmut show

100%

No pip install mutmut

100%

Exact value assertions

100%

Boundary condition tests

100%

Non-member below threshold

100%

mutation-summary.md scores

100%

workflow completeness

100%

79%

16%

Strengthen Test Suite with Mutation Testing

TypeScript Vitest stryker config

Criteria

Baseline

With context

Correct vitest package

100%

Core package installed

100%

Config filename

100%

testRunner vitest

100%

packageManager bun

coverageAnalysis perTest

100%

Correct thresholds

50%

incremental enabled

100%

mutate pattern

100%

reporters configured

62%

100%

bunx stryker run

mutation-report.md created

100%

Repository: secondsky/claude-skills
Path: plugins/mutation-testing/skills/mutation-testing/SKILL.md
Commit: c4889f6

Evaluated: 5 months ago
Agent: Claude Code
Model: Claude Sonnet 4.6

Table of Contents

Strengthen Test Suite with Mutation Testing Add Mutation Testing to a Bun-Native Test Suite Improve Python Test Quality Using Mutation Testing

Is this your skill?

If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.