Babysitter Stryker Mutation Testing

Stryker mutation testing for assessing test suite quality and effectiveness

install

source · Clone the upstream repo

git clone https://github.com/a5c-ai/babysitter

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/a5c-ai/babysitter "$T" && mkdir -p ~/.claude/skills && cp -r "$T/library/specializations/qa-testing-automation/skills/stryker-mutation" ~/.claude/skills/a5c-ai-babysitter-stryker-mutation-testing && rm -rf "$T"

manifest: library/specializations/qa-testing-automation/skills/stryker-mutation/SKILL.md

Stryker Mutation Testing Skill

Overview

This skill provides expert-level capabilities for Stryker-based mutation testing, enabling test quality assessment by introducing code mutations and measuring test effectiveness.

Capabilities

Mutation Execution

Configure Stryker for JavaScript/TypeScript
Execute mutation testing runs
Configure mutation operators

Score Analysis

Analyze mutation score
Track killed vs survived mutants
Identify weak test assertions

Configuration

Configure mutators and test runners
Set up file patterns for mutation
Configure timeout settings

Reporting

Generate HTML mutation reports
Dashboard integration for tracking
CI/CD report generation

Optimization

Configure incremental mutation testing
Optimize mutation runs for large codebases
Parallel mutation execution

Test Quality Insights

Identify gaps in test coverage
Recommend assertion improvements
Prioritize test enhancements

Target Processes

```
mutation-testing.js
```
- Mutation testing implementation
```
quality-gates.js
```
- Mutation score gates
```
shift-left-testing.js
```
- Early test quality validation

Dependencies

```
@stryker-mutator/core
```
- Stryker core
Test runner plugins (jest-runner, karma-runner)
Reporter plugins

Usage Example

{
  kind: 'skill',
  skill: {
    name: 'stryker-mutation',
    context: {
      action: 'execute',
      configFile: 'stryker.conf.json',
      mutate: ['src/**/*.ts'],
      thresholds: {
        high: 80,
        low: 60,
        break: 50
      }
    }
  }
}

Configuration

The skill uses

stryker.conf.json

stryker.conf.js

and supports incremental testing for faster feedback.