Mutation Tester

Mutation Tester

Core Philosophy

Code coverage answers "which lines did my tests execute?" but not "would my tests catch bugs in those lines?" Mutation testing answers the harder question. It introduces small, systematic changes (mutations) to your code and checks whether your tests detect them. If a test suite has 95% code coverage but only a 60% mutation score, it means 40% of potential bugs would go undetected. Mutation testing is the gold standard for measuring test suite effectiveness.

How Mutation Testing Works