The button TesterWii is, as its name implies, a button tester for the Wii, however, only original Nintendo controller to test (apart from Gamcube Controller), ie Nunchuck's, etc. third-party capabilities are most likely not.

Some features are:

Test of all Wiimote Buttons
Test of all Wii Nunchuck Buttons
Nunchuk-Stick Test
Test of all controller buttons Gamcube
Test of the two sticks Gamcube
Test of all Classic Controller (Pro) buttons
Test of all Classic Controller (Pro) sticks
-Playing a test.mp3

Source- wii-homebrew