diff --git a/CHANGELOG.md b/CHANGELOG.md
index a77d3aa0..2fe165ce 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## [1.12.1](https://github.com/googleapis/python-dialogflow-cx/compare/v1.12.0...v1.12.1) (2022-06-03)
+
+
+### Bug Fixes
+
+* **deps:** require protobuf <4.0.0dev ([#396](https://github.com/googleapis/python-dialogflow-cx/issues/396)) ([51be5ca](https://github.com/googleapis/python-dialogflow-cx/commit/51be5ca187e68f17af53e6a41e59bb4cc04086c1))
+
+
+### Documentation
+
+* fix changelog header to consistent size ([#395](https://github.com/googleapis/python-dialogflow-cx/issues/395)) ([f21bc73](https://github.com/googleapis/python-dialogflow-cx/commit/f21bc7349da7fabe50cc5fb846db43e15da8b71d))
+
 ## [1.12.0](https://github.com/googleapis/python-dialogflow-cx/compare/v1.11.0...v1.12.0) (2022-05-09)
 
 
@@ -49,7 +61,7 @@
 
 * clarified wording around Cloud Storage usage ([61fd2dc](https://github.com/googleapis/python-dialogflow-cx/commit/61fd2dc3512e4bcfdfc51cf085cc12cbbf1e043b))
 
-### [1.9.1](https://github.com/googleapis/python-dialogflow-cx/compare/v1.9.0...v1.9.1) (2022-03-05)
+## [1.9.1](https://github.com/googleapis/python-dialogflow-cx/compare/v1.9.0...v1.9.1) (2022-03-05)
 
 
 ### Bug Fixes
@@ -155,7 +167,7 @@
 * added notes on long running operation ([1383bf8](https://www.github.com/googleapis/python-dialogflow-cx/commit/1383bf82b8b2ae0cd92d81768a693a2732a53a46))
 * **v3beta1:** added long running operation explanation for several apis ([977e2aa](https://www.github.com/googleapis/python-dialogflow-cx/commit/977e2aa9c17c235d125c633a6f4ba9f5a1dade7b))
 
-### [1.3.2](https://www.github.com/googleapis/python-dialogflow-cx/compare/v1.3.1...v1.3.2) (2021-09-24)
+## [1.3.2](https://www.github.com/googleapis/python-dialogflow-cx/compare/v1.3.1...v1.3.2) (2021-09-24)
 
 
 ### Bug Fixes
@@ -168,7 +180,7 @@
 * **samples:** added filter sample ([#171](https://www.github.com/googleapis/python-dialogflow-cx/issues/171)) ([5b7e6b9](https://www.github.com/googleapis/python-dialogflow-cx/commit/5b7e6b9fcb066e823d58c5ce3af0f32a54d896bc))
 * **samples:** added page management samples ([#152](https://www.github.com/googleapis/python-dialogflow-cx/issues/152)) ([41d15f8](https://www.github.com/googleapis/python-dialogflow-cx/commit/41d15f8f212baab09222c6a350efc3376a3bf9ea))
 
-### [1.3.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v1.3.0...v1.3.1) (2021-08-31)
+## [1.3.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v1.3.0...v1.3.1) (2021-08-31)
 
 
 ### Documentation
@@ -217,7 +229,7 @@
 * **v3beta1:** deprecate legacy logging settings ([96141a1](https://www.github.com/googleapis/python-dialogflow-cx/commit/96141a11fdba3dcb2a77a261505583bba75fcc77))
 * **v3:** deprecate legacy logging settings ([24ef477](https://www.github.com/googleapis/python-dialogflow-cx/commit/24ef4773d4f6392ff39e7cdf70ff67b64ee50449))
 
-### [1.1.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v1.1.0...v1.1.1) (2021-07-24)
+## [1.1.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v1.1.0...v1.1.1) (2021-07-24)
 
 
 ### Bug Fixes
@@ -264,7 +276,7 @@
 * added notes to train agent before sending queries ([#111](https://www.github.com/googleapis/python-dialogflow-cx/issues/111)) ([8a53800](https://www.github.com/googleapis/python-dialogflow-cx/commit/8a5380055dfa7d58f83be5ce0da310318b54fc51))
 * omit mention of Python 2.7 in 'CONTRIBUTING.rst' ([#1127](https://www.github.com/googleapis/python-dialogflow-cx/issues/1127)) ([#110](https://www.github.com/googleapis/python-dialogflow-cx/issues/110)) ([40974f5](https://www.github.com/googleapis/python-dialogflow-cx/commit/40974f56c27833ab23575426f75d0868e1a10d94)), closes [#1126](https://www.github.com/googleapis/python-dialogflow-cx/issues/1126)
 
-### [0.7.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v0.7.0...v0.7.1) (2021-06-16)
+## [0.7.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v0.7.0...v0.7.1) (2021-06-16)
 
 
 ### Bug Fixes
@@ -327,7 +339,7 @@
 * clarify resource format for session response. ([20df7c3](https://www.github.com/googleapis/python-dialogflow-cx/commit/20df7c3bfabef5da23970512a3f925f4dfe7d2f9))
 * Update docs on Pages, Session, Version, etc. ([20df7c3](https://www.github.com/googleapis/python-dialogflow-cx/commit/20df7c3bfabef5da23970512a3f925f4dfe7d2f9))
 
-### [0.4.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v0.4.0...v0.4.1) (2021-03-07)
+## [0.4.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v0.4.0...v0.4.1) (2021-03-07)
 
 
 ### Documentation
@@ -372,7 +384,7 @@
 
 * add v3 ([#21](https://www.github.com/googleapis/python-dialogflow-cx/issues/21)) ([97c7fb5](https://www.github.com/googleapis/python-dialogflow-cx/commit/97c7fb53e5f6af7d8b0fea3043c60da9ee1f549b))
 
-### [0.1.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v0.1.0...v0.1.1) (2020-11-17)
+## [0.1.1](https://www.github.com/googleapis/python-dialogflow-cx/compare/v0.1.0...v0.1.1) (2020-11-17)
 
 
 ### Bug Fixes
diff --git a/samples/snippets/requirements.txt b/samples/snippets/requirements.txt
index 062ed1c6..0e7d5d0a 100644
--- a/samples/snippets/requirements.txt
+++ b/samples/snippets/requirements.txt
@@ -1,2 +1,2 @@
-google-cloud-dialogflow-cx==1.11.0
+google-cloud-dialogflow-cx==1.12.0
 Flask==2.1.2
diff --git a/setup.py b/setup.py
index 8614e50c..1b831896 100644
--- a/setup.py
+++ b/setup.py
@@ -19,7 +19,7 @@
 import os
 import setuptools  # type: ignore
 
-version = "1.12.0"
+version = "1.12.1"
 
 package_root = os.path.abspath(os.path.dirname(__file__))
 
@@ -49,7 +49,8 @@
         # Until this issue is closed
         # https://github.com/googleapis/google-cloud-python/issues/10566
         "google-api-core[grpc] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
-        "proto-plus >= 1.15.0",
+        "proto-plus >= 1.15.0, <2.0.0dev",
+        "protobuf >= 3.19.0, <4.0.0dev",
     ),
     python_requires=">=3.6",
     classifiers=[
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index b666ca6c..ec8ca201 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -7,3 +7,4 @@
 # Then this file should have foo==1.14.0
 google-api-core==1.31.5
 proto-plus==1.15.0
+protobuf==3.19.0
diff --git a/testing/constraints-3.7.txt b/testing/constraints-3.7.txt
index e69de29b..ec8ca201 100644
--- a/testing/constraints-3.7.txt
+++ b/testing/constraints-3.7.txt
@@ -0,0 +1,10 @@
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List *all* library dependencies and extras in this file.
+# Pin the version to the lower bound.
+#
+# e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
+# Then this file should have foo==1.14.0
+google-api-core==1.31.5
+proto-plus==1.15.0
+protobuf==3.19.0
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_agents.py b/tests/unit/gapic/dialogflowcx_v3/test_agents.py
index bf3c1c22..6554f093 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_agents.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_agents.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_changelogs.py b/tests/unit/gapic/dialogflowcx_v3/test_changelogs.py
index e0b97063..539de01b 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_changelogs.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_changelogs.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_deployments.py b/tests/unit/gapic/dialogflowcx_v3/test_deployments.py
index e53050fe..437635cd 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_deployments.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_deployments.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_entity_types.py b/tests/unit/gapic/dialogflowcx_v3/test_entity_types.py
index d205edfe..e83e289c 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_entity_types.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_entity_types.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_environments.py b/tests/unit/gapic/dialogflowcx_v3/test_environments.py
index c5dfd501..36dc2154 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_environments.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_environments.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_experiments.py b/tests/unit/gapic/dialogflowcx_v3/test_experiments.py
index 49ee9734..3f1fa9be 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_experiments.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_experiments.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_flows.py b/tests/unit/gapic/dialogflowcx_v3/test_flows.py
index 9c9c07f0..e0b2f7fd 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_flows.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_flows.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_intents.py b/tests/unit/gapic/dialogflowcx_v3/test_intents.py
index 627b92fc..419e64ed 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_intents.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_intents.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_pages.py b/tests/unit/gapic/dialogflowcx_v3/test_pages.py
index 8086a804..5e60fe98 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_pages.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_pages.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_security_settings_service.py b/tests/unit/gapic/dialogflowcx_v3/test_security_settings_service.py
index c8745cbb..906759f2 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_security_settings_service.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_security_settings_service.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_session_entity_types.py b/tests/unit/gapic/dialogflowcx_v3/test_session_entity_types.py
index d73fc941..74647255 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_session_entity_types.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_session_entity_types.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_sessions.py b/tests/unit/gapic/dialogflowcx_v3/test_sessions.py
index 30b7fde9..0a19ca0c 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_sessions.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_sessions.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_test_cases.py b/tests/unit/gapic/dialogflowcx_v3/test_test_cases.py
index 8b897c0b..9b4ecd55 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_test_cases.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_test_cases.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_transition_route_groups.py b/tests/unit/gapic/dialogflowcx_v3/test_transition_route_groups.py
index bb104847..c1c2a4d4 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_transition_route_groups.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_transition_route_groups.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_versions.py b/tests/unit/gapic/dialogflowcx_v3/test_versions.py
index cdf25596..55e8d1aa 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_versions.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_versions.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3/test_webhooks.py b/tests/unit/gapic/dialogflowcx_v3/test_webhooks.py
index d135a78c..1c11a7c0 100644
--- a/tests/unit/gapic/dialogflowcx_v3/test_webhooks.py
+++ b/tests/unit/gapic/dialogflowcx_v3/test_webhooks.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_agents.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_agents.py
index a2d1735e..7999e013 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_agents.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_agents.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_changelogs.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_changelogs.py
index e8504693..cd2791d0 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_changelogs.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_changelogs.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_deployments.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_deployments.py
index 12653ba6..16b1d6a9 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_deployments.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_deployments.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_entity_types.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_entity_types.py
index 1f7c14f9..10be9fbc 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_entity_types.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_entity_types.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_environments.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_environments.py
index 74605d99..f8f956c7 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_environments.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_environments.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_experiments.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_experiments.py
index 52db5677..2b230d05 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_experiments.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_experiments.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_flows.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_flows.py
index d5c36248..6c38830f 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_flows.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_flows.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_intents.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_intents.py
index b124e8ad..36a02f48 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_intents.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_intents.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_pages.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_pages.py
index 7963e811..e4e4817e 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_pages.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_pages.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_security_settings_service.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_security_settings_service.py
index 14f81030..ea0d2c51 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_security_settings_service.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_security_settings_service.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_session_entity_types.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_session_entity_types.py
index aebb3157..ab9e1d92 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_session_entity_types.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_session_entity_types.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_sessions.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_sessions.py
index 2bd51d19..975f6295 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_sessions.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_sessions.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_test_cases.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_test_cases.py
index 75e425bf..035efde8 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_test_cases.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_test_cases.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_transition_route_groups.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_transition_route_groups.py
index 5255ef2c..3ce6db75 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_transition_route_groups.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_transition_route_groups.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_versions.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_versions.py
index de2a668b..ae7b8935 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_versions.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_versions.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio
diff --git a/tests/unit/gapic/dialogflowcx_v3beta1/test_webhooks.py b/tests/unit/gapic/dialogflowcx_v3beta1/test_webhooks.py
index b263e238..ff1c09ab 100644
--- a/tests/unit/gapic/dialogflowcx_v3beta1/test_webhooks.py
+++ b/tests/unit/gapic/dialogflowcx_v3beta1/test_webhooks.py
@@ -14,7 +14,13 @@
 # limitations under the License.
 #
 import os
-import mock
+
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
 
 import grpc
 from grpc.experimental import aio