diff --git a/iot/google/cloud/iot_v1/gapic/device_manager_client.py b/iot/google/cloud/iot_v1/gapic/device_manager_client.py
index 0331ed1a4118..2753f75a8d83 100644
--- a/iot/google/cloud/iot_v1/gapic/device_manager_client.py
+++ b/iot/google/cloud/iot_v1/gapic/device_manager_client.py
@@ -112,7 +112,7 @@ def __init__(self,
                  transport=None,
                  channel=None,
                  credentials=None,
-                 client_config=device_manager_client_config.config,
+                 client_config=None,
                  client_info=None):
         """Constructor.
 
@@ -145,13 +145,20 @@ def __init__(self,
                 your own client library.
         """
         # Raise deprecation warnings for things we want to go away.
-        if client_config:
-            warnings.warn('The `client_config` argument is deprecated.',
-                          PendingDeprecationWarning)
+        if client_config is not None:
+            warnings.warn(
+                'The `client_config` argument is deprecated.',
+                PendingDeprecationWarning,
+                stacklevel=2)
+        else:
+            client_config = device_manager_client_config.config
+
         if channel:
             warnings.warn(
                 'The `channel` argument is deprecated; use '
-                '`transport` instead.', PendingDeprecationWarning)
+                '`transport` instead.',
+                PendingDeprecationWarning,
+                stacklevel=2)
 
         # Instantiate the transport.
         # The transport is responsible for handling serialization and
diff --git a/iot/google/cloud/iot_v1/gapic/transports/device_manager_grpc_transport.py b/iot/google/cloud/iot_v1/gapic/transports/device_manager_grpc_transport.py
index 69513fe2a82d..d90a41405c08 100644
--- a/iot/google/cloud/iot_v1/gapic/transports/device_manager_grpc_transport.py
+++ b/iot/google/cloud/iot_v1/gapic/transports/device_manager_grpc_transport.py
@@ -65,6 +65,8 @@ def __init__(self,
                 credentials=credentials,
             )
 
+        self._channel = channel
+
         # gRPC uses objects called "stubs" that are bound to the
         # channel and provide a basic method for each RPC.
         self._stubs = {
@@ -95,6 +97,15 @@ def create_channel(cls,
             scopes=cls._OAUTH_SCOPES,
         )
 
+    @property
+    def channel(self):
+        """The gRPC channel used by the transport.
+
+        Returns:
+            grpc.Channel: A gRPC channel object.
+        """
+        return self._channel
+
     @property
     def create_device_registry(self):
         """Return the gRPC stub for {$apiMethod.name}.
diff --git a/iot/synth.py b/iot/synth.py
index e8700e749720..a29841920a22 100644
--- a/iot/synth.py
+++ b/iot/synth.py
@@ -29,3 +29,5 @@
     artman_output_name='iot-v1')
 
 s.move(library / 'google/cloud/iot_v1')
+s.move(library / 'tests/unit/gapic')
+s.move(library / 'tests/system/gapic')
diff --git a/iot/tests/system/gapic/v1/test_system_device_manager_v1.py b/iot/tests/system/gapic/v1/test_system_device_manager_v1.py
index c42e12536473..911426bf4079 100644
--- a/iot/tests/system/gapic/v1/test_system_device_manager_v1.py
+++ b/iot/tests/system/gapic/v1/test_system_device_manager_v1.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+#
 # Copyright 2018 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/iot/tests/unit/gapic/v1/test_device_manager_client_v1.py b/iot/tests/unit/gapic/v1/test_device_manager_client_v1.py
index b632e5cec3a3..d4f1b0ce83ec 100644
--- a/iot/tests/unit/gapic/v1/test_device_manager_client_v1.py
+++ b/iot/tests/unit/gapic/v1/test_device_manager_client_v1.py
@@ -1,3 +1,5 @@
+# -*- coding: utf-8 -*-
+#
 # Copyright 2018 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -13,6 +15,7 @@
 # limitations under the License.
 """Unit tests."""
 
+import mock
 import pytest
 
 from google.cloud import iot_v1
@@ -73,7 +76,10 @@ def test_create_device_registry(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         parent = client.location_path('[PROJECT]', '[LOCATION]')
@@ -91,7 +97,10 @@ def test_create_device_registry(self):
     def test_create_device_registry_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         parent = client.location_path('[PROJECT]', '[LOCATION]')
@@ -109,7 +118,10 @@ def test_get_device_registry(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         name = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -126,7 +138,10 @@ def test_get_device_registry(self):
     def test_get_device_registry_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         name = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -143,7 +158,10 @@ def test_update_device_registry(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         device_registry = {}
@@ -161,7 +179,10 @@ def test_update_device_registry(self):
     def test_update_device_registry_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         device_registry = {}
@@ -172,7 +193,10 @@ def test_update_device_registry_exception(self):
 
     def test_delete_device_registry(self):
         channel = ChannelStub()
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         name = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -188,7 +212,10 @@ def test_delete_device_registry(self):
     def test_delete_device_registry_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         name = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -210,7 +237,10 @@ def test_list_device_registries(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         parent = client.location_path('[PROJECT]', '[LOCATION]')
@@ -229,7 +259,10 @@ def test_list_device_registries(self):
 
     def test_list_device_registries_exception(self):
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         parent = client.location_path('[PROJECT]', '[LOCATION]')
@@ -254,7 +287,10 @@ def test_create_device(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         parent = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -272,7 +308,10 @@ def test_create_device(self):
     def test_create_device_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         parent = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -297,7 +336,10 @@ def test_get_device(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -314,7 +356,10 @@ def test_get_device(self):
     def test_get_device_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -339,7 +384,10 @@ def test_update_device(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         device = {}
@@ -357,7 +405,10 @@ def test_update_device(self):
     def test_update_device_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         device = {}
@@ -368,7 +419,10 @@ def test_update_device_exception(self):
 
     def test_delete_device(self):
         channel = ChannelStub()
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -384,7 +438,10 @@ def test_delete_device(self):
     def test_delete_device_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -407,7 +464,10 @@ def test_list_devices(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         parent = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -425,7 +485,10 @@ def test_list_devices(self):
 
     def test_list_devices_exception(self):
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         parent = client.registry_path('[PROJECT]', '[LOCATION]', '[REGISTRY]')
@@ -443,7 +506,10 @@ def test_modify_cloud_to_device_config(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -462,7 +528,10 @@ def test_modify_cloud_to_device_config(self):
     def test_modify_cloud_to_device_config_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -480,7 +549,10 @@ def test_list_device_config_versions(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -498,7 +570,10 @@ def test_list_device_config_versions(self):
     def test_list_device_config_versions_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -515,7 +590,10 @@ def test_list_device_states(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -533,7 +611,10 @@ def test_list_device_states(self):
     def test_list_device_states_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         name = client.device_path('[PROJECT]', '[LOCATION]', '[REGISTRY]',
@@ -551,7 +632,10 @@ def test_set_iam_policy(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         resource = client.registry_path('[PROJECT]', '[LOCATION]',
@@ -570,7 +654,10 @@ def test_set_iam_policy(self):
     def test_set_iam_policy_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         resource = client.registry_path('[PROJECT]', '[LOCATION]',
@@ -589,7 +676,10 @@ def test_get_iam_policy(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         resource = client.registry_path('[PROJECT]', '[LOCATION]',
@@ -607,7 +697,10 @@ def test_get_iam_policy(self):
     def test_get_iam_policy_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         resource = client.registry_path('[PROJECT]', '[LOCATION]',
@@ -624,7 +717,10 @@ def test_test_iam_permissions(self):
 
         # Mock the API response
         channel = ChannelStub(responses=[expected_response])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup Request
         resource = client.registry_path('[PROJECT]', '[LOCATION]',
@@ -643,7 +739,10 @@ def test_test_iam_permissions(self):
     def test_test_iam_permissions_exception(self):
         # Mock the API response
         channel = ChannelStub(responses=[CustomException()])
-        client = iot_v1.DeviceManagerClient(channel=channel)
+        patch = mock.patch('google.api_core.grpc_helpers.create_channel')
+        with patch as create_channel:
+            create_channel.return_value = channel
+            client = iot_v1.DeviceManagerClient()
 
         # Setup request
         resource = client.registry_path('[PROJECT]', '[LOCATION]',