Changed checking of cover state closed from 0 to closed_position vari…

…able. (#18407)

Change error message to avoid expression "get_position_topic".

homeassistant/components/cover/mqtt.py

@@ -87,7 +87,7 @@ def validate_options(value):
     if (CONF_SET_POSITION_TOPIC in value and
             CONF_GET_POSITION_TOPIC not in value):
         raise vol.Invalid(
-            "Set position topic must be set together with get position topic.")
+            "set_position_topic must be set together with position_topic.")
     return value
 
 
@@ -287,7 +287,7 @@ def position_message_received(topic, payload, qos):
                         float(payload), COVER_PAYLOAD)
                 if 0 <= percentage_payload <= 100:
                     self._position = percentage_payload
-                    self._state = self._position == 0
+                    self._state = self._position == self._position_closed
             else:
                 _LOGGER.warning(
                     "Payload is not integer within range: %s",
@@ -451,7 +451,7 @@ async def async_set_cover_position(self, **kwargs):
             mqtt.async_publish(self.hass, self._set_position_topic,
                                position, self._qos, self._retain)
             if self._optimistic:
-                self._state = percentage_position == 0
+                self._state = percentage_position == self._position_closed
                 self._position = percentage_position
                 self.async_schedule_update_ha_state()