Add matter node added subscription (#84377)

homeassistant/components/matter/adapter.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 from typing import TYPE_CHECKING
 
 from chip.clusters import Objects as all_clusters
+from matter_server.common.models.events import EventType
 from matter_server.common.models.node_device import AbstractMatterNodeDevice
 
 from homeassistant.config_entries import ConfigEntry
@@ -42,10 +43,18 @@ class MatterAdapter:
         self.platform_handlers[platform] = add_entities
 
     async def setup_nodes(self) -> None:
-        """Set up all existing nodes."""
+        """Set up all existing nodes and subscribe to new nodes."""
         for node in await self.matter_client.get_nodes():
             self._setup_node(node)
 
+        def node_added_callback(event: EventType, node: MatterNode) -> None:
+            """Handle node added event."""
+            self._setup_node(node)
+
+        self.config_entry.async_on_unload(
+            self.matter_client.subscribe(EventType.NODE_ADDED, node_added_callback)
+        )
+
     def _setup_node(self, node: MatterNode) -> None:
         """Set up an node."""
         LOGGER.debug("Setting up entities for node %s", node.node_id)

tests/components/matter/test_adapter.py

@@ -3,13 +3,16 @@ from __future__ import annotations
 
 from unittest.mock import MagicMock
 
+from matter_server.common.helpers.util import dataclass_from_dict
+from matter_server.common.models.events import EventType
+from matter_server.common.models.node import MatterNode
 import pytest
 
 from homeassistant.components.matter.const import DOMAIN
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers import device_registry as dr
 
-from .common import setup_integration_with_node_fixture
+from .common import load_and_parse_node_fixture, setup_integration_with_node_fixture
 
 
 async def test_device_registry_single_node_device(
@@ -80,3 +83,29 @@ async def test_device_registry_bridge(
     assert device2_entry.model == "Mock Light"
     assert device2_entry.hw_version is None
     assert device2_entry.sw_version == "1.49.1"
+
+
+async def test_node_added_subscription(
+    hass: HomeAssistant,
+    matter_client: MagicMock,
+    integration: MagicMock,
+) -> None:
+    """Test subscription to new devices work."""
+    assert matter_client.subscribe.call_count == 1
+    assert matter_client.subscribe.call_args[0][0] == EventType.NODE_ADDED
+
+    node_added_callback = matter_client.subscribe.call_args[0][1]
+    node_data = load_and_parse_node_fixture("onoff-light")
+    node = dataclass_from_dict(
+        MatterNode,
+        node_data,
+    )
+
+    entity_state = hass.states.get("light.mock_onoff_light")
+    assert not entity_state
+
+    node_added_callback(EventType.NODE_ADDED, node)
+    await hass.async_block_till_done()
+
+    entity_state = hass.states.get("light.mock_onoff_light")
+    assert entity_state