Add more HomeKit device enumeration tests (#22194)

* Test that Aqara Gateway, Ecobee 3 and Lennox E30 is correctly enumerated

* Move json to fixtures directory

* Move IO to executor

tests/components/homekit_controller/common.py

@@ -1,5 +1,6 @@
 """Code to support homekit_controller tests."""
 import json
+import os
 from datetime import timedelta
 from unittest import mock
 
@@ -13,7 +14,8 @@ from homeassistant.components.homekit_controller.const import (
     DOMAIN, HOMEKIT_ACCESSORY_DISPATCH)
 from homeassistant.setup import async_setup_component
 import homeassistant.util.dt as dt_util
-from tests.common import async_fire_time_changed, fire_service_discovered
+from tests.common import (
+    async_fire_time_changed, fire_service_discovered, load_fixture)
 
 
 class FakePairing:
@@ -149,10 +151,13 @@ class FakeService(AbstractService):
         return char
 
 
-def setup_accessories_from_file(path):
+async def setup_accessories_from_file(hass, path):
     """Load an collection of accessory defs from JSON data."""
-    with open(path, 'r') as accessories_data:
-        accessories_json = json.load(accessories_data)
+    accessories_fixture = await hass.async_add_executor_job(
+        load_fixture,
+        os.path.join('homekit_controller', path),
+    )
+    accessories_json = json.loads(accessories_fixture)
 
     accessories = []