Define RemoteEntity entity attributes as class variables (#51904)

homeassistant/components/remote/__init__.py

@@ -145,20 +145,24 @@ async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
 class RemoteEntity(ToggleEntity):
     """Base class for remote entities."""
 
+    _attr_activity_list: list[str] | None = None
+    _attr_current_activity: str | None = None
+    _attr_supported_features: int = 0
+
     @property
     def supported_features(self) -> int:
         """Flag supported features."""
-        return 0
+        return self._attr_supported_features
 
     @property
     def current_activity(self) -> str | None:
         """Active activity."""
-        return None
+        return self._attr_current_activity
 
     @property
     def activity_list(self) -> list[str] | None:
         """List of available activities."""
-        return None
+        return self._attr_activity_list
 
     @final
     @property