I'll try and find out...how, I don't know, because there won't be an honest answer if it is not a good look.
As far as pre-race goes, they only test Grp and listed race runners as far as I know, and I can't think of one here this year in the pre-lockdown period. None after, obviously.
Hard for the officials at Riccarton, though, as there is no allocation of stalls. They wander around aimlessly asking ' have you seen xxx '
Definitely swabbing post -race, though I can't answer as to what happens to those swabs. I would like to think all is above board.
I remember, a few years ago, having the constabulary at the stables one race morning to test a runner in a listed sprint.
We wandered out to the yards, caught the subject, took bloods, and off they went. I could have done anything to him once they'd left the premises!
I told the vet at the races later that we brought out the drugs once they'd gone...but he knew me well and just rolled his eyes.