It turns out that `pytest-anki` does what we are trying to do already.
Note that `empty_anki_session_started` creates a temporary user too.
We are “overwriting“ it in `profile_created_and_loaded`
by calling `temporary_user`. It seems that doing this is safe.
Previously, tests were run against Anki launched by user.
Now,
* most tests run against isolated Anki in current process;
* tests in `test_server.py` launch another Anki in a separate process
and run a few commands to test the server;
* nearly all tests were preserved in the sense that
what was being tested is tested still.
A few tests in `test_graphical.py` are skipped due to
a problem with the method tests, see the comments;
* tests can be run:
* In a single profile, using --no-tear-down-profile-after-each-test;
* In a single app instance, but with the profile being torn down
after each test--default;
* In separate processes, using --forked.
