if you're interviewing someone and your interviews questions can be answered by a quick google, maybe you should think that during the course of a work day, the same applies and you should think about a test that actually tests skills involved in the work the candidate will be doing
i have no problem with a candidate doing something totally by themself in part 2 of 5 before in in person interview; theres still another 3 different interviews (many of which will be in person) to catch cheating and such
it's just a filter; it's not the interview