Originally Posted by
ScottFromWI 
Most companies don't drug test specifically for alcohol, mainly for other drugs. But the only way you will know is to ask this employer specifically.
In addition to that, even if they did test for it, alcohol is legal (assuming you're of legal age). What you did in your own time is irrelevant, I would think.
However, if you're worried about your drinking and taking this extra job, as you say, specifically to keep you from drinking in the evenings, do you really think that will be enough long term?