We tried for a little while to have an online test (HackerRank) before we interviewed, but we removed it when we got feedback that the really good people (who probably already had a job and/or existing offers) just didn't bother.
It's really unfortunate, because a lot of companies that go through great lengths to ensure they pick good candidates do so because they are small and one bad hire could really hurt the company. But the fact is, larger companies are less discriminant with their hiring, and usually pay better too. So when faced with the option of doing yet another programming quiz for a company or accepting the job offer I have in hand, it makes sense to just accept.