I don't remember his name, but one of the creators of Angular said (paraphrasing) "When choosing between libraries and in doubt, choose the one that has more testing in place". This is something I've personally found true the majority of the time.
Which kind of testing? Is it better for a library to be in wide distribution and therefore battle-tested but without unit tests, or to be unpopular but full of unit tests?
It depends on the size the library. I'm sure people will point to some outliers but I'd hard-pressed to find a large library that is both widely distributed and severely lacking in tests.
