I was never allowed to test out of classes. I always asked when I felt it was reasonable, and always met with the same response. Though I did have a couple of great professors who would stay with me after class occasionally to talk about whatever I was working on at the time.
I had one class that I wasn't allowed to test out of during my second to last semester. The professor told us that all of the assignments were up on the portal for the class. I asked him if I could turn in all of the assignments the first week of class. He said yes but wasn't sure that I'd know the material. I arranged a deal that I would turn in all of the assignments the first week and as long as I got an A on every assignment, he would give me the final the at the beginning of the third week and I wouldn't have to show up to class again if I got an A. It's not always easy, and sometimes you've got to get dean/provost approval, but if you really want to do something, you can most likely do it.
