message: pipette config unit tests clean up files.
  closes
diff: @@ -166,18 +166,26 @@ def test_override_save(ot_config_tempdir):
  assert new_pconf.quirks == []
  -def test_mutable_configs_only(monkeypatch):
  +@pytest.fixture
  +def new_id_for_save() -> str:
  + """Fixture to provide a pipette id then delete it's generated file."""
  + r = 'aoa2109j09cj2a'
  + yield r
  +
  + (CONFIG['pipette_config_overrides_dir'] / f'{r}.json').unlink()
  +
  +
  +def test_mutable_configs_only(monkeypatch, new_id_for_save):
  # Test that only set mutable configs are populated in this dictionary
  monkeypatch.setattr(
  pipette_config, 'MUTABLE_CONFIGS', ['tipLength', 'plungerCurrent'])
  - new_id = 'aoa2109j09cj2a'
  model = 'p300_multi_v1'
  - pipette_config.save_overrides(new_id, {}, model)
  + pipette_config.save_overrides(new_id_for_save, {}, model)
  - config = pipette_config.list_mutable_configs(new_id)
  + config = pipette_config.list_mutable_configs(new_id_for_save)
  # instead of dealing with unordered lists, convert to set and check whether
  # these lists have a difference between them
  difference = set(list(config.keys())) - \
  @@ -269,8 +277,12 @@ async def attached_pipettes(hardware, request):
  }
  }
  await hardware.cache_instruments()
  - return {k.name.lower(): v
  - for k, v in hardware._backend._attached_instruments.items()}
  + yield {k.name.lower(): v for k, v in
  + hardware._backend._attached_instruments.items()}
  +
  + # Delete created config files
  + (CONFIG['pipette_config_overrides_dir'] / 'abc123.json').unlink()
  + (CONFIG['pipette_config_overrides_dir'] / 'abcd123.json').unlink()
  async def test_override(attached_pipettes):
  