Cast the volume_level of a universal media_player to a float (home-as…

…sistant#29045)

* Make sure to cast the volume_level of a universal media_player to a float

* Fix test that expects the wrong bahaviour

* Catch exception instead of checking for None

homeassistant/components/universal/media_player.py

@@ -255,7 +255,10 @@ def state(self):
     @property
     def volume_level(self):
         """Volume level of entity specified in attributes or active child."""
-        return self._override_or_child_attr(ATTR_MEDIA_VOLUME_LEVEL)
+        try:
+            return float(self._override_or_child_attr(ATTR_MEDIA_VOLUME_LEVEL))
+        except (TypeError, ValueError):
+            return None
 
     @property
     def is_volume_muted(self):

tests/components/universal/test_media_player.py

@@ -539,10 +539,10 @@ def test_volume_level_children_and_attr(self):
 
         ump = universal.UniversalMediaPlayer(self.hass, **config)
 
-        assert "0" == ump.volume_level
+        assert 0 == ump.volume_level
 
         self.hass.states.set(self.mock_volume_id, 100)
-        assert "100" == ump.volume_level
+        assert 100 == ump.volume_level
 
     def test_is_volume_muted_children_and_attr(self):
         """Test is volume muted property w/ children and attrs."""