Mutation Testing

Expert knowledge for mutation testing - validating that your tests actually catch bugs by introducing deliberate code mutations.

Core Concept

• Mutants: Small code changes introduced automatically
• Killed: Test fails with mutation (good - test caught the bug)
• Survived: Test passes with mutation (bad - weak test)
• Score: Percentage of mutants killed (aim for 80%+)

TypeScript/JavaScript (Stryker)

Vitest Runner

Installation