At the same time, it is intensely wild to me that their "then" is an alternative to their "should", which apparently just re-executes the callback it's given until that callback stops throwing. If your tests require to be re-run an arbitrary and varying number of times in order to pass, you have problems that need to be dealt with in some better way than having your test harness paper over them automatically for you.

If a small standard library is using it for things that aren't promises, you can bet your ass that there are javascript libraries using it for things that aren't promises.

Like I said, I just chose to look at rust first because it's documentation has a good search bar.