A related method. Not quite as straightforward as running with and without the failing test and comparing coverage reports. This technique goes through and collects many test runs and identifies lines only associated with or most often associated with failing runs.

That's the whole point of coverage diffs.

The tough ones are the tests that sometimes fail and give you the same coverage results - the problem is not in the code under test! And the lazy/common things to do are re-run the test or add a sleep to make things "work."