Tests don't work. Fiverr tried this already and it was a fiasco. Tests were flawed and outdated, among other things.
Even today's English test that Fiverr requires you to pass if you want to activate a writing or proofreading gig is flawed. And, worse, the answers can be found on the internet. So, here on the forum you get to see sellers, whose English is as bad as it can be, offering English content writing and English proofing gigs because they got to pass Fiverr's test.
That's the ugly truth, and I guess we'll have to live with it.