They ideally should find their way by themselves.
> You don’t need to import the fixture you want to use in a test,
> it automatically gets discovered by pytest. The discovery of fixture
> functions starts at test classes, then test modules, then conftest.py
> files and finally builtin and third party plugins.>
>
> — [pytest docs](https://docs.pytest.org/en/4.6.x/fixture.html#conftest-py-sharing-fixture-functions)
Add a Pytest fixture that returns an UpdaterThread instance which has
its own unique settings directory. Note that the UpdaterThread instance
needs to be slightly nerfed, so that it doesn't rely on Qt functionality
or any isolation providers.
