Add unique_id to WOL integration (#49604)

Co-authored-by: Franck Nijhof <git@frenck.dev>

homeassistant/components/wake_on_lan/switch.py

@@ -14,6 +14,7 @@ from homeassistant.const import (
     CONF_MAC,
     CONF_NAME,
 )
+from homeassistant.helpers import device_registry as dr
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.script import Script
 
@@ -87,6 +88,7 @@ class WolSwitch(SwitchEntity):
         )
         self._state = False
         self._assumed_state = host is None
+        self._unique_id = dr.format_mac(mac_address)
 
     @property
     def is_on(self):
@@ -108,6 +110,11 @@ class WolSwitch(SwitchEntity):
         """Return false if assumed state is true."""
         return not self._assumed_state
 
+    @property
+    def unique_id(self):
+        """Return the unique id of this switch."""
+        return self._unique_id
+
     def turn_on(self, **kwargs):
         """Turn the device on."""
         service_kwargs = {}