TIL, I figured it was something of a legal gray area. Funnily enough, World's Strongest Man tests for party drugs but not PEDs, as can be seen when Mariusz Pudzianowski popped for something (either cocaine or cannabis) back in 2004. I think it'd be interesting to see how things would shake out if WSM or strongman in general did start testing for PEDs. It'd have to be a new class like how powerlifting does it though to keep the records straight.