Handle GA Disconnect intent (#21387)

* Handle GA Disconnect intent

* Fixed lint error

homeassistant/components/google_assistant/smart_home.py

@@ -187,7 +187,7 @@ async def async_handle_message(hass, config, message):
     """Handle incoming API messages."""
     response = await _process(hass, config, message)
 
-    if 'errorCode' in response['payload']:
+    if response and 'errorCode' in response['payload']:
         _LOGGER.error('Error handling message %s: %s',
                       message, response['payload'])
 
@@ -215,7 +215,6 @@ async def _process(hass, config, message):
 
     try:
         result = await handler(hass, config, inputs[0].get('payload'))
-        return {'requestId': request_id, 'payload': result}
     except SmartHomeError as err:
         return {
             'requestId': request_id,
@@ -228,6 +227,10 @@ async def _process(hass, config, message):
             'payload': {'errorCode': ERR_UNKNOWN_ERROR}
         }
 
+    if result is None:
+        return None
+    return {'requestId': request_id, 'payload': result}
+
 
 @HANDLERS.register('action.devices.SYNC')
 async def async_devices_sync(hass, config, payload):
@@ -337,6 +340,15 @@ async def handle_devices_execute(hass, config, payload):
     return {'commands': final_results}
 
 
+@HANDLERS.register('action.devices.DISCONNECT')
+async def async_devices_disconnect(hass, config, payload):
+    """Handle action.devices.DISCONNECT request.
+
+    https://developers.google.com/actions/smarthome/create#actiondevicesdisconnect
+    """
+    return None
+
+
 def turned_off_response(message):
     """Return a device turned off response."""
     return {

tests/components/google_assistant/test_smart_home.py

@@ -316,3 +316,15 @@ async def test_empty_name_doesnt_sync(hass):
             'devices': []
         }
     }
+
+
+async def test_query_disconnect(hass):
+    """Test a disconnect message."""
+    result = await sh.async_handle_message(hass, BASIC_CONFIG, {
+        'inputs': [
+            {'intent': 'action.devices.DISCONNECT'}
+        ],
+        'requestId': REQ_ID
+    })
+
+    assert result is None