Hi @FlemmingVesterg,
Just to let you know, the /undelete URL is completely unsupported by Instructure, and is one of the main reasons (as far as I'm aware) that you don't see any documentation about it, other than a few people mentioning it in the community. I believe it was originally intended to be a tool that Canvas Support personnel could use to quickly recover content, but I'm not sure about that. I would not rely on that tool too much.
The Test/Beta environment s are documented:
But even with the official documentation, those areas are generally not something a teacher would work in very often (and students are almost always denied access outright to these environments). As an admin, I have to be very careful what Canvas environment I'm working in, as it's easy to switch to a tab in Test/Beta and think I'm in the normal Canvas environment. When this happens, any of the work done in test/beat doesn't apply to the normal Canvas environment. That could be a lot of lost work for faculty.
Aside from the Canvas API, intended mostly for programmers, I don't think there are really any secret/hidden URLs that a teacher or student should be using in Canvas.
Hope this helps!
-Chris
