I am a california Attorney, but your question seems to be a basic one. Mainly, you have to comply with the provisions set forth in Diversion. You must also comply with the rules that Probation has set forth. If Diversion says you are to abstain from alcohol use, that means you can not drink anything regardless of whether you are testing or not. If however diversion's rules state do not state any restrictions for the consumption of alcohol after you have completed the testing portion of the program, (and probation does not have any restrictions on drinking), then you should be able to consume "a beer at your house or something". The easiest way to find out, is to simply call your contact at Diversion ( and also call Probation), and ask them if you are allowed to drink after testing is complete and find out exactly what the alcohol consumption rules are.
Your diversion agreement is set by law. Part of the agreement requires you to complete treatment, which requires sobriety and proof. Once you have a certificate of successful completion, you can have alcohol.
Without reading the terms of your bench probation, it is not possible to tell what was written in the terms.
You would do best to call and check with your attorney. He or she will have all the paperwork and be able to tell you about your county's local rules and interpretations.