Testing is a thing you have to do when making things, so why not have a whole stage dedicated to it?
Test Stage is exactly what it sounds like, just a stage I use to test features of the mod. It'll be included as a bonus stage for getting a currently undecided amount of emblems.
The Blue room, mostly used to test Halfpipe Utilities.
More of the Blue room, plus a peek at the Red room, which is filled with every enemy in the game.
Finally, the Green and Yellow rooms, used to test Sheilds and FoFs respectively.
I cut a few things out of these rooms as to not spoil anything yet, that's why they look much emptier :p