Yes, i agree, testing will be fun for sure
but the system for comparing mouse movements and determining what the player has performed will be rather complex. I think about this algorithm:
-get mouse movement speed lets say, every 0.1 second and put it into array.
-record 'perfect' trick movements, and save them into some file.
-compare the performed movement with all saved movements, if they are very similar, player performs a trick, otherwise he bails