I think you're right Mione, but it is an interesting question nonetheless. Sure he would be allowed to do magic and all, but what would the career prospects for him or anyone else in his class if they hadn't taen them.

My guess would be though that in the years they didn't have the end of year exams they still had O.W.L.s and N.E.W.T.s as they are conducted by the ministry, not the school. So, I think Cedric and his year would have been fine.