Does an employer have to give everyone a drug test if only one person was showing concerns for one?

I have been running a small business for the owner whom wanted to sell it so I did a trial period of completely running it alone along with his other employee, the other employee was causing some alarming actions and wasn't respecting my position in charge. I informed the owner and he had him take a drug test. Then the day I had two appointments with customers he told me he made him take a drug test and wanted me to. I told him I would but expressed if I was late to these customers we would lose a lot of money, he aid I could take it tomorrow, but I ended up losing my last appointment from the owner trying to mediate me and the other employee. The owner then took me to the drug screening place and I refused and left because of him making me lose this appointment he said he understood and then the next day told me he trusted me and would not be needing me to take the test. Two days later fired me for refusing a test, and wrote the reason he conducted me to take one was for suspicion ?? When I was the one who came to him of a issue with some one else. I get pated commission and havnt received a w2 or pay