Fix Monoprice robustness (#33869)

* Silently handle update failures

* Limite parallel updates

* Remove return values

* Remove trailing return

* Add test for empty update

homeassistant/components/monoprice/media_player.py

@@ -1,6 +1,8 @@
 """Support for interfacing with Monoprice 6 zone home audio controller."""
 import logging
 
+from serial import SerialException
+
 from homeassistant import core
 from homeassistant.components.media_player import MediaPlayerDevice
 from homeassistant.components.media_player.const import (
@@ -18,6 +20,8 @@ from .const import CONF_SOURCES, DOMAIN, SERVICE_RESTORE, SERVICE_SNAPSHOT
 
 _LOGGER = logging.getLogger(__name__)
 
+PARALLEL_UPDATES = 1
+
 SUPPORT_MONOPRICE = (
     SUPPORT_VOLUME_MUTE
     | SUPPORT_VOLUME_SET
@@ -127,9 +131,15 @@ class MonopriceZone(MediaPlayerDevice):
 
     def update(self):
         """Retrieve latest state."""
-        state = self._monoprice.zone_status(self._zone_id)
+        try:
+            state = self._monoprice.zone_status(self._zone_id)
+        except SerialException:
+            _LOGGER.warning("Could not update zone %d", self._zone_id)
+            return
+
         if not state:
-            return False
+            return
+
         self._state = STATE_ON if state.power else STATE_OFF
         self._volume = state.volume
         self._mute = state.mute
@@ -138,7 +148,6 @@ class MonopriceZone(MediaPlayerDevice):
             self._source = self._source_id_name[idx]
         else:
             self._source = None
-        return True
 
     @property
     def entity_registry_enabled_default(self):

tests/components/monoprice/test_media_player.py

@@ -294,6 +294,58 @@ async def test_update(hass):
     assert state.attributes[ATTR_INPUT_SOURCE] == "three"
 
 
+async def test_failed_update(hass):
+    """Test updating failure from monoprice."""
+    monoprice = MockMonoprice()
+    await _setup_monoprice(hass, monoprice)
+
+    # Changing media player to new state
+    await _call_media_player_service(
+        hass, SERVICE_VOLUME_SET, {"entity_id": ZONE_1_ID, "volume_level": 0.0}
+    )
+    await _call_media_player_service(
+        hass, SERVICE_SELECT_SOURCE, {"entity_id": ZONE_1_ID, "source": "one"}
+    )
+
+    monoprice.set_source(11, 3)
+    monoprice.set_volume(11, 38)
+
+    with patch.object(MockMonoprice, "zone_status", side_effect=SerialException):
+        await async_update_entity(hass, ZONE_1_ID)
+        await hass.async_block_till_done()
+
+    state = hass.states.get(ZONE_1_ID)
+
+    assert state.attributes[ATTR_MEDIA_VOLUME_LEVEL] == 0.0
+    assert state.attributes[ATTR_INPUT_SOURCE] == "one"
+
+
+async def test_empty_update(hass):
+    """Test updating with no state from monoprice."""
+    monoprice = MockMonoprice()
+    await _setup_monoprice(hass, monoprice)
+
+    # Changing media player to new state
+    await _call_media_player_service(
+        hass, SERVICE_VOLUME_SET, {"entity_id": ZONE_1_ID, "volume_level": 0.0}
+    )
+    await _call_media_player_service(
+        hass, SERVICE_SELECT_SOURCE, {"entity_id": ZONE_1_ID, "source": "one"}
+    )
+
+    monoprice.set_source(11, 3)
+    monoprice.set_volume(11, 38)
+
+    with patch.object(MockMonoprice, "zone_status", return_value=None):
+        await async_update_entity(hass, ZONE_1_ID)
+        await hass.async_block_till_done()
+
+    state = hass.states.get(ZONE_1_ID)
+
+    assert state.attributes[ATTR_MEDIA_VOLUME_LEVEL] == 0.0
+    assert state.attributes[ATTR_INPUT_SOURCE] == "one"
+
+
 async def test_supported_features(hass):
     """Test supported features property."""
     await _setup_monoprice(hass, MockMonoprice())