Mutation Testing

Value: Feedback -- mutation testing closes the verification loop by proving that tests actually detect the bugs they claim to prevent. Without it, passing tests may provide false confidence.

Purpose

Teaches the agent to run mutation testing as a quality gate before PR creation. Mutation testing makes small changes (mutations) to production code and checks whether tests catch them. Surviving mutants reveal gaps where bugs could hide undetected. The required mutation kill rate is 100%.

Practices

Detect and Run the Right Tool

Detect the project type and run the appropriate mutation testing tool.