Your Tests Pass. Your Mutation Score Is 40%. Here's What Surviving Mutants Are Actually Telling You.
Code coverage says you're safe. Mutation testing says your tests are mostly decoration. Here's how surviving mutants expose the gap, and how to close it.
Your tests pass. Your coverage report says 87%. But your mutation score is 40%, and half your mutants are still alive. That 40% doesn't mean your code is…