Improve error when HomeKit accessory underlying entity is missing (#51713)

* Improve error when HomeKit accessory underlying entity is missing

* docstring in test

tests/components/homekit/test_homekit.py

@@ -54,7 +54,15 @@ from homeassistant.const import (
 )
 from homeassistant.core import State
 from homeassistant.helpers import device_registry
-from homeassistant.helpers.entityfilter import generate_filter
+from homeassistant.helpers.entityfilter import (
+    CONF_EXCLUDE_DOMAINS,
+    CONF_EXCLUDE_ENTITIES,
+    CONF_EXCLUDE_ENTITY_GLOBS,
+    CONF_INCLUDE_DOMAINS,
+    CONF_INCLUDE_ENTITIES,
+    CONF_INCLUDE_ENTITY_GLOBS,
+    convert_filter,
+)
 from homeassistant.setup import async_setup_component
 from homeassistant.util import json as json_util
 
@@ -65,6 +73,27 @@ from tests.common import MockConfigEntry, mock_device_registry, mock_registry
 IP_ADDRESS = "127.0.0.1"
 
 
+def generate_filter(
+    include_domains,
+    include_entities,
+    exclude_domains,
+    exclude_entites,
+    include_globs=None,
+    exclude_globs=None,
+):
+    """Generate an entity filter using the standard method."""
+    return convert_filter(
+        {
+            CONF_INCLUDE_DOMAINS: include_domains,
+            CONF_INCLUDE_ENTITIES: include_entities,
+            CONF_EXCLUDE_DOMAINS: exclude_domains,
+            CONF_EXCLUDE_ENTITIES: exclude_entites,
+            CONF_INCLUDE_ENTITY_GLOBS: include_globs or [],
+            CONF_EXCLUDE_ENTITY_GLOBS: exclude_globs or [],
+        }
+    )
+
+
 @pytest.fixture(autouse=True)
 def always_patch_driver(hk_driver):
     """Load the hk_driver fixture."""
@@ -1173,6 +1202,31 @@ async def test_homekit_start_in_accessory_mode(
     assert homekit.status == STATUS_RUNNING
 
 
+async def test_homekit_start_in_accessory_mode_missing_entity(
+    hass, hk_driver, mock_zeroconf, device_reg, caplog
+):
+    """Test HomeKit start method in accessory mode when entity is not available."""
+    entry = await async_init_integration(hass)
+
+    homekit = _mock_homekit(hass, entry, HOMEKIT_MODE_ACCESSORY)
+
+    homekit.bridge = Mock()
+    homekit.bridge.accessories = []
+    homekit.driver = hk_driver
+    homekit.driver.accessory = Accessory(hk_driver, "any")
+
+    with patch(f"{PATH_HOMEKIT}.HomeKit.add_bridge_accessory") as mock_add_acc, patch(
+        f"{PATH_HOMEKIT}.show_setup_message"
+    ), patch("pyhap.accessory_driver.AccessoryDriver.async_start"):
+        await homekit.async_start()
+
+    await hass.async_block_till_done()
+    mock_add_acc.assert_not_called()
+    assert homekit.status == STATUS_WAIT
+
+    assert "entity not available" in caplog.text
+
+
 async def test_wait_for_port_to_free(hass, hk_driver, mock_zeroconf, caplog):
     """Test we wait for the port to free before declaring unload success."""
     await async_setup_component(hass, "persistent_notification", {})