Draft: Start refactoring to add tests for #43

I'm starting to explore the code with the concrete goal of fixing #43.

In the process, I'm refactoring things to allow for tests in the way I described during my LAS and GNOME-Latam talks.

I'll have a better description once the refactoring is done, and hence I am marking this as a draft. I haven't gotten down to the bug, or being able to have a test for it yet, but I'm getting there. In the meantime, I'm making this draft MR just for you to see the line of development, and to see if you are interested 😄

If you start reading the MR, please do read the commit messages; my explanation of the refactoring steps is there.