As we might be changing the collision environment soon, and I haven't gotten around to doing this after #1439, tests for the subframe functionality will be very helpful.

This issue can teach you how to write tests and should be easy enough to implement with the help of this tutorial. The motions and commands in the subframe tutorial make some good test cases.

Related to #643, which is also still a great WMD issue.

Also I know this is my unfinished business, but that's how I know it's not hard, so 🙇‍♂️