Visual Controller Test by Mr. Reaper is a button pressing application for Wii.

Release notes:

0.9 = Added in everything but the kitchen sink (but if I had a kitchen sink wii attachment for Cooking Mama, I’d add that too). You should be able to test just about everything now, on any port, including the tap bar on some guitars and the analog shoulder buttons on an original Classic Controller. Oh, you can even test the Power button on your wiimote by holding it down for 3 seconds.