That's the part I meant when i said "known regressions". If there is a bug, you write the test, it doesn't happen again... Until next refactor, because most oft

That's the part I meant when i said "known regressions". If there is a bug, you write the test, it doesn't happen again... Until next refactor, because most often you'll find that the tests were written at a lower level, instead of a functional test (that tests the e2e functionality) it was written to test individual pieces of SUT such as individual methods in a class. This happens quite a lot. Devs will prefer unit tests over more complex e2e tests which takes a lot more effort to write (because they are slow, flaky, more complex). Any friction in this process will make the dev prefer the easier way to test (which does not mean future proof).