This is all wrong. When you have enough people working on a codebase such that not everyone knows everything about it, tests are a great way to document the behavior. They're much better than something like a wiki, in fact, because nobody actually keeps that kind of documentation up to date.
I'm not arguing that tests are useless. I'm arguing that tests are usually impossible. I invite you to suggest a test for https://github.com/VCVRack/Rack for example that could either 1) have prevented a bug, or 2) document the software's behavior.
