mine.mutation-test

Mutation testing validates test suite effectiveness by intentionally introducing semantic bugs into source code and verifying that test cases detect them. It analyzes code targets like files or modules, executes mutations, and reports killed versus survived mutants to expose coverage gaps.

To check if tests catch real bugs, run mutation testing on specific files or modules. The process introduces logic flips and guard removals, executes your tests against these mutations, and highlights any surviving mutations where your tests failed to detect the injected defects.

Yes, you can target mutation testing at specific code targets such as individual files, functions, or modules. The testing process identifies mutation points within these specified boundaries based on bug categories and evaluates test case detection for each targeted scope.

When a mutation survives, it indicates a weakness in your test coverage. You must manually write new test cases targeting the surviving mutation to improve coverage, ensuring your test suite can successfully detect that specific semantic bug if it occurs in production.

Mutation testing complements rather than replaces standard code coverage by verifying test suite effectiveness rather than just execution paths. While coverage measures which lines run, mutation testing introduces actual semantic bugs to confirm your tests can detect faulty logic and incorrect boundary conditions.

Tests pass while mutants survive because standard tests execute code paths without asserting all edge cases. Surviving mutants reveal that while the code ran, the tests lacked assertions to catch specific semantic bugs like logic flips or removed guard conditions, requiring manual test writing.