Don't think theres testing in Pro League, but there should be. I am certain there is testing in all competetive internationals, but probably not in friendlies.
As we're on the subject of drug testing, I asked Sancho which English players shirt he got in Germany (coz I think he got Santa Cruz from Paraguay) and he said he was supposed to get Rooneys, but as they were walking off, Rooney was selected for testing and had to keep his shirt on.
I also knew an English player, John Mackie, who captained Leyton Orient to the League 2 title, which they won on the last match of the season. As the guys celebrated, he was selected for testing. He got so vex with the 4th official, he got red carded 10 mins after the match had finished. He wasn't even allowed to drink the champagne or celebrate on the field until he gave his sample. It can often take a player up to 60 mins to provide a sample due to dehydration, despite drinking litres of water.