> For the complete documentation index, see [llms.txt](https://hanfak.gitbook.io/workspace/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hanfak.gitbook.io/workspace/testing-reading-maintaining/testing-1/mutation-testing.md).

# Mutation testing

## Code coverage

* Example - Pitest
* Changing the code and see if it breaks the test
* Can take a long time
  * but can store the data, then on the next time can run the tests on the delta
* Much better than doing code coverage via lines hit
* <https://journal.optivem.com/p/code-coverage-vs-mutation-testing>

## Issues

* <https://mail.google.com/mail/u/0/?tab=wm#inbox/FMfcgzGqQJlfVkwPHWjQbPPfkQGcPJnB>
* <https://testing.googleblog.com/2021/04/mutation-testing.html>
* \[Kill All Mutants! (Intro to Mutation Testing) by Dave Aronson]\(<https://www.youtube.com/watch?v=ahfhOCrG1z4>]