The Absolute Beginner’s Guide To Mutation Testing - Neal Brooks

Have you ever sweated away for months and finally achieved 100% coverage, but your customers still complained about bugs? Do you never feel satisfied that you can fully rely on your tests, even though you have data providers with all sorts of weird values in them? Are you certain that at least one test would fail if you introduced an error into any given line of code in the codebase? Do you have less than 100% confidence in your test suite?
How can you be sure that the code your colleague wants to merge to `main` via the `super-new-feature-branch` is adequately tested beyond the ‘coveralls’ report?