Have you had experience using mutation testing in your projects?

Mutation testing is a method of assessing test quality by making small changes (mutations) to the code and checking whether the tests can detect these changes. I personally used mutation testing in Java projects with the PIT (Pitest) tool. It helped identify coverage gaps and improve test quality.

Example of using PIT:

mvn org.pitest:pitest-maven:mutationCoverage

After running, a report is generated showing which mutations were 'killed' by tests and which were not. This helps understand which parts of the code are insufficiently tested.