The test allocates a lot of memory inside the JS execution engine. On some of our testing platforms this can take a long time. I think the best solution is to account for the possibility of the JS being interrupted because this takes too long. I also considered increasing the timeout value during this test.

I could also see an argument that the test should be deleted since the assertion here is just testing that we apply the validation on insert - it's not really specific to javascript or mapReduce. I think it's worth having coverage for creating an object in JS larger than the limit nonetheless, and also to ensure we don't ever go through some internal backdoor which circumvents this limit.