Add tests suite

[Serene-Arc]

I thought it would be good to have this draft PR open so that we can discuss bugs that the tests reveal as I find them.

First one is a bug I've been trying to nail dain for a while: @Neurrone what is the reason that the path of the items were used to sort instead of the name? There's a comment that specifies that it needs to be that way but not why. I've made a bunch of test cases to check sorting under different naming schemes and the paths mess up, while the names do not (so far).

If you remember the use cases that necessitate using the path, could you please tell them so I can add them to the tests? It's possible that a more complex sorting algorithm will be required but it needs tests before I can start working on a test.