Use STATE_UNKNOWN constant in dlink and ecobee (#39948)

homeassistant/components/dlink/switch.py

@@ -13,6 +13,7 @@ from homeassistant.const import (
     CONF_NAME,
     CONF_PASSWORD,
     CONF_USERNAME,
+    STATE_UNKNOWN,
     TEMP_CELSIUS,
 )
 import homeassistant.helpers.config_validation as cv
@@ -145,14 +146,14 @@ class SmartPlugData:
                 _LOGGER.warning("Waiting %s s to retry", retry_seconds)
                 return
 
-        _state = "unknown"
+        _state = STATE_UNKNOWN
 
         try:
             self._last_tried = dt_util.now()
             _state = self.smartplug.state
         except urllib.error.HTTPError:
             _LOGGER.error("D-Link connection problem")
-        if _state == "unknown":
+        if _state == STATE_UNKNOWN:
             self._n_tried += 1
             self.available = False
             _LOGGER.warning("Failed to connect to D-Link switch")

homeassistant/components/ecobee/sensor.py

@@ -5,6 +5,7 @@ from homeassistant.const import (
     DEVICE_CLASS_HUMIDITY,
     DEVICE_CLASS_TEMPERATURE,
     PERCENTAGE,
+    STATE_UNKNOWN,
     TEMP_FAHRENHEIT,
 )
 from homeassistant.helpers.entity import Entity
@@ -108,7 +109,11 @@ class EcobeeSensor(Entity):
     @property
     def state(self):
         """Return the state of the sensor."""
-        if self._state in [ECOBEE_STATE_CALIBRATING, ECOBEE_STATE_UNKNOWN, "unknown"]:
+        if self._state in [
+            ECOBEE_STATE_CALIBRATING,
+            ECOBEE_STATE_UNKNOWN,
+            STATE_UNKNOWN,
+        ]:
             return None
 
         if self.type == "temperature":