One of my questions has been answered really comprehensively, and it does answer the question in theory, but I haven't tested the answer, and don't understand the code so well. Do I accept because the question was answered in theory and a very good answer, or do I wait until I've tested it first and understand it properly?
In this particular case, it is the only answer to my question.
Accepted answer means "This answer helped me (the most)".
You have two things that you can do:
Accept it, test it, and unaccept if it's wrong (you can unaccept whenever you want). Leave a comment as well explaining why you think it didn't work.
Test it first and then accept it. There's no hurry, no matter what irate commenters may tell you. In fact, when a question of mine is quickly answered, I wait for others to answer it before accepting one. In such cases, I usually comment "I'll accept this answer once I've tested it/let others see it".
There is no hurry. Try out the suggestions provided in the answer, see if it really answers your question. If not, ask follow up questions in the comments and/or update your question with specifics to get a more elaborate answer.
+1 for the 1st part of your answer. -1 for the help-vampirey part of the second part of your answer.
-1 for the part about updating the question with specifics if the question is unclear?
I'd suggest waiting awhile, especially if the question only has one answer. You never know when someone else might write another, better one, but people are less likely to contribute more answers if one has been accepted already.
I sometimes see people accept the first answer they see that sort-of helps, and seemingly never notice another, better answer that's added later (or at least, they never accept the better one instead). I think that's unfortunate.
