Tests build FakeDevices named "TestDevice". Any test that touches
device.settings or device.persister without mocking
configuration.persister (e.g. test_device_complex, test_device_battery)
calls the real configuration.persister(), which loads and rewrites
~/.config/solaar/config.yaml — the TestDevice has no stable identity
so it never matches an existing entry, and a fresh blank TestDevice
entry is appended on every test run.
Add an autouse conftest fixture that points configuration's yaml/json
paths at a per-test tmp_path and clears the cached _config. No test
can reach the real config now, and each test starts from an empty
config instead of inheriting entries from earlier tests.
Ken Sanislo