Discard duplicate sonos events (#64722)

* Throttle duplicate Sonos events

* Fix test by breaking reference

homeassistant/components/sonos/speaker.py

@@ -427,12 +427,16 @@ class SonosSpeaker:
 
         self.speaker_activity(f"{event.service.service_type} subscription")
 
+        # Skip if this update is an unchanged subset of the previous event
+        if last_event := self._last_event_cache.get(event.service.service_type):
+            if event.variables.items() <= last_event.items():
+                return
+
+        # Save most recently processed event variables for cache and diagnostics
+        self._last_event_cache[event.service.service_type] = event.variables
         dispatcher = self._event_dispatchers[event.service.service_type]
         dispatcher(event)
 
-        # Save most recent event variables for diagnostics
-        self._last_event_cache[event.service.service_type] = event.variables
-
     @callback
     def async_dispatch_alarms(self, event: SonosEvent) -> None:
         """Add the soco instance associated with the event to the callback."""

tests/components/sonos/conftest.py

@@ -1,4 +1,5 @@
 """Configuration for Sonos tests."""
+from copy import copy
 from unittest.mock import AsyncMock, MagicMock, Mock, patch
 
 import pytest
@@ -36,6 +37,7 @@ class SonosMockEvent:
 
         Assumes value has a format of <str>:<int>.
         """
+        self.variables = copy(self.variables)
         base, count = self.variables[var_name].split(":")
         newcount = int(count) + 1
         self.variables[var_name] = ":".join([base, str(newcount)])