Actually, it usually depends on the department not individual professors. In some departments you can test out of classes for credit, in others you can test ou

Actually, it usually depends on the department not individual professors. In some departments you can test out of classes for credit, in others you can test out of prerequisites so you can move directly to more advanced classes but you don't get credit, and in others you can get credit for some classes but not others. From what I have seen, credit tends to be most available for math classes, many computer science courses will let you test out of lower level (especially language) prerequisites but often won't give you credit for them, and engineering departments will often let you test out of math and science and lower-level departmental courses, but limit the amount of credit you can earn this way. And some courses, especially English and other humanities, sometimes actually take roll and penalize you if you aren't filling a seat.