this was discussed not too long ago. for more in depth info search. no there is no test for superdrol. it will shut down your natural test so if they test for low test levels they gotcha.
People can have naturally low test levels for any number of reasons. Factors in your diet can even suppress testosterone. They don't flag low test levels, only HIGH test levels. Especially since having low test levels is a DISadvantage.
As for Superdrol, just because they don't test for the compound itself, doesn't mean it isn't detectable necessarily. Many many compounds share metabolites. A ton of steroids show up when you test for nandrolone for example. IIRC trenbolone registers nandrolone positive.
I'm not sure what kind of metabolites methasteron has. However, from what sledge said, it seems it is a very targetted compound with few metabolites; unlike something like say Dianabol. He called Dianabol a "shotgun" effect, whereas Superdrol is more like a laser. So it could be that methasteron really doesn't show up in any current tests. If that's true though, I would think it would have been out on the Olympic circuit already for a while now.