mutation-testing-generator

Mutation testing measures test suite quality by automatically modifying code to create mutations, then running your tests to see if they catch the changes. Surviving mutations indicate weak tests or redundant code that lacks adequate coverage.

To configure Stryker for mutation testing, you need to set up appropriate mutators, test runners, and file exclusions. This configuration allows the tool to systematically inject changes and evaluate your test suite's effectiveness.

Yes, mutation testing can be applied when a test suite is already in place. It works with your existing Vitest or Jest setup to objectively assess test thoroughness and identify gaps in coverage.

Code coverage measures which lines of code are executed by tests, while mutation testing evaluates test effectiveness by checking if tests actually fail when code is altered, highlighting weak tests that coverage metrics miss.

Surviving mutations occur when your tests pass despite code modifications, indicating weak tests or redundant code. This means your tests execute the code but lack assertions robust enough to detect unintended behavioral changes.

Mutation testing is not suitable for projects lacking a comprehensive test suite. It requires an existing test suite to evaluate, and running it can be computationally expensive, making it less ideal for early development stages.