The Big book of AA suggests this for an alcoholic test: go to the bar and try to do some controlled drinking. Have two drinks and then stop suddenly and quit for the day. If doubts continue to persist then try the experiment a few more times. I would take this a step further and suggest that you do this every day for 30 days straight with no exceptions. Two drinks per day, then stop.
What will this do? If you are a true alcoholic, then passing this 30 day trial is not very likely, though there may be a rare person who can white knuckle it through the experiment without losing control. A real alcoholic will not be able to restrain themselves consistently. This is a big part of the key here: consistently.
See, denial is very prevalent when dealing with alcoholics because we can fool ourselves some of the time very easily. For example, take any drunk and put them up to the ultimate test and tell them to prove for one day that they are not an alcoholic. Ask them to abstain for 24 hours and prove their worth, then you will leave them alone forever. Can they do it? Heck yes they can do it….making it through 24 hours is like nothing if they can then drink themselves silly for the rest of their days!
And so it is with your average alcoholic who runs into trouble with a DUI or gets into a big spat with their spouse: they can fool themselves for a day or two, or maybe even for a few weeks or a few months. But eventually, the get into trouble again, and the drinking takes over again. They will have “just one” and be off to the races. And so, denial is such that the average alcoholic can fool themselves, because they will hang on tight to the memory of when they could control their drinking, but forget about all of the times when they lost control. The truth is, they actually could control it for a day. But most of the time, it still gets them into trouble. More often than not, the booze is controlling them, not the other way around.
Another test that might be illustrative is to simply abstain from all alcohol for 30 days and see what type of reaction you get. For some alcoholics, this will be very difficult as well, and they will not, in most cases, even agree to conducting such an experiment. Far too difficult when it is so much easier to just keep self medicating.