Fix Nest doing I/O inside event loop (#4855)

homeassistant/components/sensor/nest.py

@@ -128,13 +128,20 @@ class NestSensor(Entity):
 
         # device specific
         self._location = self.device.where
-        self._name = self.device.name_long
+        self._name = "{} {}".format(self.device.name_long,
+                                    self.variable.replace("_", " "))
         self._state = None
+        self._unit = None
 
     @property
     def name(self):
         """Return the name of the nest, if any."""
-        return "{} {}".format(self._name, self.variable.replace("_", " "))
+        return self._name
+
+    @property
+    def unit_of_measurement(self):
+        """Return the unit the value is expressed in."""
+        return self._unit
 
 
 class NestBasicSensor(NestSensor):
@@ -145,13 +152,10 @@ class NestBasicSensor(NestSensor):
         """Return the state of the sensor."""
         return self._state
 
-    @property
-    def unit_of_measurement(self):
-        """Return the unit the value is expressed in."""
-        return SENSOR_UNITS.get(self.variable, None)
-
     def update(self):
         """Retrieve latest state."""
+        self._unit = SENSOR_UNITS.get(self.variable, None)
+
         if self.variable == 'operation_mode':
             self._state = getattr(self.device, "mode")
         else:
@@ -161,14 +165,6 @@ class NestBasicSensor(NestSensor):
 class NestTempSensor(NestSensor):
     """Representation of a Nest Temperature sensor."""
 
-    @property
-    def unit_of_measurement(self):
-        """Return the unit the value is expressed in."""
-        if self.device.temperature_scale == 'C':
-            return TEMP_CELSIUS
-        else:
-            return TEMP_FAHRENHEIT
-
     @property
     def state(self):
         """Return the state of the sensor."""
@@ -176,6 +172,11 @@ class NestTempSensor(NestSensor):
 
     def update(self):
         """Retrieve latest state."""
+        if self.device.temperature_scale == 'C':
+            self._unit = TEMP_CELSIUS
+        else:
+            self._unit = TEMP_FAHRENHEIT
+
         temp = getattr(self.device, self.variable)
         if temp is None:
             self._state = None