Ensure discovery can setup legacy device tracker platforms (#114101)

homeassistant/components/device_tracker/__init__.py

@@ -69,15 +69,7 @@ def is_on(hass: HomeAssistant, entity_id: str) -> bool:
 
 async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
     """Set up the device tracker."""
-    #
-    # Legacy and platforms load in a non-awaited tracked task
-    # to ensure device tracker setup can continue and config
-    # entry integrations are not waiting for legacy device
-    # tracker platforms to be set up.
-    #
-    hass.async_create_task(
-        async_setup_legacy_integration(hass, config), eager_start=True
-    )
+    async_setup_legacy_integration(hass, config)
     return True
 
 

homeassistant/components/device_tracker/legacy.py

@@ -201,9 +201,47 @@ def see(
     hass.services.call(DOMAIN, SERVICE_SEE, data)
 
 
-async def async_setup_integration(hass: HomeAssistant, config: ConfigType) -> None:
+@callback
+def async_setup_integration(hass: HomeAssistant, config: ConfigType) -> None:
+    """Set up the legacy integration."""
+    # The tracker is loaded in the _async_setup_integration task so
+    # we create a future to avoid waiting on it here so that only
+    # async_platform_discovered will have to wait in the rare event
+    # a custom component still uses the legacy device tracker discovery.
+    tracker_future: asyncio.Future[DeviceTracker] = hass.loop.create_future()
+
+    async def async_platform_discovered(
+        p_type: str, info: dict[str, Any] | None
+    ) -> None:
+        """Load a platform."""
+        platform = await async_create_platform_type(hass, config, p_type, {})
+
+        if platform is None or platform.type != PLATFORM_TYPE_LEGACY:
+            return
+
+        tracker = await tracker_future
+        await platform.async_setup_legacy(hass, tracker, info)
+
+    discovery.async_listen_platform(hass, DOMAIN, async_platform_discovered)
+    #
+    # Legacy and platforms load in a non-awaited tracked task
+    # to ensure device tracker setup can continue and config
+    # entry integrations are not waiting for legacy device
+    # tracker platforms to be set up.
+    #
+    hass.async_create_task(
+        _async_setup_integration(hass, config, tracker_future), eager_start=True
+    )
+
+
+async def _async_setup_integration(
+    hass: HomeAssistant,
+    config: ConfigType,
+    tracker_future: asyncio.Future[DeviceTracker],
+) -> None:
     """Set up the legacy integration."""
     tracker = await get_tracker(hass, config)
+    tracker_future.set_result(tracker)
 
     async def async_see_service(call: ServiceCall) -> None:
         """Service to see a device."""
@@ -227,19 +265,6 @@ async def async_setup_integration(hass: HomeAssistant, config: ConfigType) -> No
     if setup_tasks:
         await asyncio.wait(setup_tasks)
 
-    async def async_platform_discovered(
-        p_type: str, info: dict[str, Any] | None
-    ) -> None:
-        """Load a platform."""
-        platform = await async_create_platform_type(hass, config, p_type, {})
-
-        if platform is None or platform.type != PLATFORM_TYPE_LEGACY:
-            return
-
-        await platform.async_setup_legacy(hass, tracker, info)
-
-    discovery.async_listen_platform(hass, DOMAIN, async_platform_discovered)
-
     # Clean up stale devices
     cancel_update_stale = async_track_utc_time_change(
         hass, tracker.async_update_stale, second=range(0, 60, 5)

tests/components/device_tracker/test_init.py

@@ -235,7 +235,8 @@ async def test_discover_platform(
     """Test discovery of device_tracker demo platform."""
     await async_setup_component(hass, "homeassistant", {})
     await async_setup_component(hass, device_tracker.DOMAIN, {})
-    await hass.async_block_till_done()
+    # async_block_till_done is intentionally missing here so we
+    # can verify async_load_platform still works without it
     with patch("homeassistant.components.device_tracker.legacy.update_config"):
         await discovery.async_load_platform(
             hass, device_tracker.DOMAIN, "demo", {"test_key": "test_val"}, {"bla": {}}
@@ -251,6 +252,31 @@ async def test_discover_platform(
     )
 
 
+async def test_discover_platform_missing_platform(
+    hass: HomeAssistant, caplog: pytest.LogCaptureFixture
+) -> None:
+    """Test discovery of device_tracker missing platform."""
+    await async_setup_component(hass, "homeassistant", {})
+    await async_setup_component(hass, device_tracker.DOMAIN, {})
+    # async_block_till_done is intentionally missing here so we
+    # can verify async_load_platform still works without it
+    with patch("homeassistant.components.device_tracker.legacy.update_config"):
+        await discovery.async_load_platform(
+            hass,
+            device_tracker.DOMAIN,
+            "its_not_there",
+            {"test_key": "test_val"},
+            {"bla": {}},
+        )
+        await hass.async_block_till_done()
+    assert device_tracker.DOMAIN in hass.config.components
+    assert (
+        "Unable to prepare setup for platform 'its_not_there.device_tracker'"
+        in caplog.text
+    )
+    # This test should not generate an unhandled exception
+
+
 async def test_update_stale(
     hass: HomeAssistant,
     mock_device_tracker_conf: list[legacy.Device],