Ok, I'm assuming that you received a standard allergy testing in which they prick your forearm with a bunch of needles with different allergens on them and they saw which ones you were allergic to. Even if this is not the testing you received, I still can answer your question.
With any allergy testing, they can tell exactly what you are allergic to. For example, I am allergic to mold, but there is a specific mold that is only found in California that I am not allergic to (name slipping my mind) The doctors can tell me exactly what I am allergic to and what I am not allergic to. I am also allergic to cats and dogs (among other animals) but I am not allergic to rabbits. If you are allergic to your rats, then you might not be allergic to a rabbit or a guinea pig, but then again you might also be allergic to them too. You should receive a report that tells you exactly what you are allergic to and how severely you are allergic.
If you want to keep your rats, may I suggest talking with your doctor about allergy shots? I have gotten them for 3 years now and they help me a lot! If you can't get them, then try Zyrtec which is found over-the-counter. Hope this helps! :D