I really don't think that a test is necessary, however, anyone who wants to play the game SHOULD know the rules, etiquette and proper course behavior. I find that ignorance and lack of respect for the game is about the same whether playing on private or public courses. Just because someone pays more or less to play does not mean they are entitled to a vacation from the rules. Public or private, I have followed more than my share of idiots and repaired more than my share of ball marks, divots, scuff marks, etc. If someone cannot demonstrate at least a basic working knowlege of the rules and etiquette, perhaps they should find another hobby.
Having said all that, how would you make certain that a player knows? Maybe the course(s) could offer classes so that people could LEARN.