were you doing this test at school or at home?
If you were at school yes I could see anything on ur screen if I wanted.
If you did it at home or away from school then the only thing I can think of is if u were copy / pasting
theres way to detect tab browsing
also if it was copy pasting and u finished the test fast and submitted well it doesnt take someone to say hey he did this test in 20 seconds hes either a genius or a cheater.