As Playher man says, the most important thing here is not to get defensive.
I would suggest next time you get hit with a **** test that accuses you of being a certain way, you ask her "what do you mean?". This works in many situations, not just with girls. It shows that you're interested in what they have to say. This will also help you see if it was a real concern she has or just a **** test.
If after asking her this you can tell that it is a real **** test you should respond with something along the lines of what TheException said, or anything else that makes fun of her comment.