Write tests

[radi-cho]

This project needs some tests to ensure everything is working...

[retrixe]

We need tests for every RSG-Group project lol
Excluding hyper-background lol that's already tested, though its compatibility with the new 2.x canary releases is yet to be seen.

[radi-cho]

Yeah, @retrixe!
So we will renew the Chess versions (the desktop and the mobile) using the API, so we'll need less tests there. The tests written for this project will be adapted for the core projects, too.

About the other RSG projects: rsg-components already has an feature-request (RSG-Group/rsg-components#12). wallpapers and lenin-cli are not ready yet, so everything is under control.