Use TestCase.addCleanup (#36560)

tests/components/rfxtrx/test_sensor.py

@@ -18,8 +18,9 @@ class TestSensorRfxtrx(unittest.TestCase):
         """Set up things to be run when tests are started."""
         self.hass = get_test_home_assistant()
         mock_component(self.hass, "rfxtrx")
+        self.addCleanup(self.tear_down_cleanup)
 
-    def tearDown(self):
+    def tear_down_cleanup(self):
         """Stop everything that was started."""
         rfxtrx_core.RECEIVED_EVT_SUBSCRIBERS = []
         rfxtrx_core.RFX_DEVICES = {}