Strikes me as one of those things that if you "need" something that massive just to test your scripttardery, you've probably done something wrong. I guess it could serve a purpose on crapplets built with web technologies given those are in themselves usually bloated train wrecks of slapped together frameworks and libraries made by people who probably shouldn't be writing JS in the first place -- but I can't see myself using it for much of anything.
Really if I had anything complex enough for that to even be needed, I'd toss the entire codebase and start over.
Though looking at AVA's codebase on github is a bit terrifying -- much like that stupid "leftpad that broke the web" it's so poorly written and ignorant of how JS even works, it's like someone blindly copied it out of an old beginners C book without taking the time to translate it more than "making it work".
Endless pointless back-to-back var for nothing, declaratory functional objects doing literal notations job, brackets for nothing on single result evaluations, if with variables for nothing doing ternary operators job, redundant checks of the same value across multiple if's, multiple String.replace doing the job of a single one, broken path handling since it's extension checking ANYWHERE in a string, using the slower foreach method on a non-complex iteration... and that's just the api.js
VERY much what I've come to expect from the code people blindly include from NPM. That's NOT a compliment!