What's a word for someone who has completed an exercise?
Solution 1:
A nice unambiguous term is those who have completed the test.
However, finisher is often used for those who have crossed the finish line in a race, and may work in your case.
finisher noun
1 a person or thing that finishes something, in particular:
• a person who reaches the end of a race or other competition:
all finishers will receive a commemorative medal[ODO]