[Ma8ee]

And it will lock the system into behaviour that might just be accidental. The value of tests is to make sure that you don't break anything that anyone cares about, not that the every little never used edge case behaviour, which might just an artefact of a specific implementation, is locked in forever.

[jeffreygoesto]

This is my experience as well. The problem is that persisting "but what _shall_ it do?" on a low level is seen as redundant, as long as everything works. Typically forgotten edge cases are detected elsewhere. The metric _that_ you ran past those code lines says nothing about that you came there for the right reason.