Title I provided is based on my experience yesterday when I was trying to bid for a project that was about providing IT support.
To be able to bid it said I need to pass level 1 US english test. I dont know if job poster wants bidders to get certified or if it is freelancer itself making that decision. Note that one has to pay about 6$ to get certified. Test is on freelancer site itself and I believe is designed by them.
The test questions are quite simple for anybody who has done English at school but I still ended up failing. The reason for failing I believe is tester gets 5 minutes to answer a ridiculous number of simple questions and it is designed so that one can't finish it in time. Basically it is designed so you retake the test and pay for it again.
This company is definitely dodgy as I had similar experience another time where I just got charged a fee for clicking a link on my email to view the job request.