testing/mutation-testing

Mutation testing verifies test suite effectiveness by automatically introducing small code mutations and measuring if your existing tests detect them. It identifies gaps in test coverage by checking whether tests fail when bugs are introduced.

To run mutation testing with Vitest and Stryker, configure your environment using stryker.config.json and execute the npm script defined in your package.json to start analyzing code changes against your test suite.

Yes, Stryker mutation testing works with Vitest through the @stryker-mutator/vitest-runner integration. It requires a JavaScript test runner like Vitest to run your existing tests against introduced mutations.

Test coverage measures which lines of code your tests execute, while mutation testing measures test effectiveness by introducing code mutations and verifying if tests detect them. Mutation testing identifies weak tests that fail to catch code changes.

Run mutation testing after implementing new features to verify that your unit tests will correctly fail if bugs are accidentally introduced during future code modifications. This ensures your test suite remains robust against regressions.

To set up mutation testing with Stryker, you need the @stryker-mutator/core and @stryker-mutator/vitest-runner dependencies, along with a configured JavaScript test runner like Vitest and a stryker.config.json file.