I've occasionally been lulled into a false sense of security by the difference between "every line is run" and "the function is fully tested". On the other han

I've occasionally been lulled into a false sense of security by the difference between "every line is run" and "the function is fully tested". On the other hand, even if I'm half-assing the unit tests, and implementing the bare minimum necessary to reach whatever arbitrary coverage% is being sought ... I still find bugs, bugs that almost certainly would have a real impact in production, even if I already ran an end-to-end test and was pretty sure it was working fine[*]. Not every time I write tests, but often enough to feel like it pays for all of the time "wasted". So even if coverage metrics maybe arbitrary, I don't really begrudge having to meet them. And honestly, once you're forced to start writing the tests just for coverage, it isn't that much extra work to make them a little more comprehensive than the floor set by coverage. [*] Honestly I'm shocked at how well buggy software works, for the most part.