Remove invalid unit of measurement in mfi (#85620)

homeassistant/components/mfi/sensor.py

@@ -133,14 +133,14 @@ class MfiSensor(SensorEntity):
         try:
             tag = self._port.tag
         except ValueError:
-            return "State"
+            return None
 
         if tag == "temperature":
             return UnitOfTemperature.CELSIUS
         if tag == "active_pwr":
             return "Watts"
         if self._port.model == "Input Digital":
-            return "State"
+            return None
         return tag
 
     def update(self) -> None:

tests/components/mfi/test_sensor.py

@@ -148,7 +148,7 @@ async def test_uom_power(port, sensor):
 async def test_uom_digital(port, sensor):
     """Test the UOM digital input."""
     port.model = "Input Digital"
-    assert sensor.unit_of_measurement == "State"
+    assert sensor.unit_of_measurement is None
     assert sensor.device_class is None
 
 
@@ -162,7 +162,7 @@ async def test_uom_unknown(port, sensor):
 async def test_uom_uninitialized(port, sensor):
     """Test that the UOM defaults if not initialized."""
     type(port).tag = mock.PropertyMock(side_effect=ValueError)
-    assert sensor.unit_of_measurement == "State"
+    assert sensor.unit_of_measurement is None
     assert sensor.device_class is None