Previously settings was implicitly tested on tests/gui/test_updater.py.
However this was concerned with updater-related tests only, which
incidentally covered almost all of settings.py. However, a few tests
were missing. This commit increases the test coverage, but also tests
additional test conditions.
The goal is to help us increase the test coverage of the previous
scenario, which tested for the persistence of user data (settings). This
way we can drop the requirement to test this on linux hosts, which is
slightly harder (more cumbersome) to do.