Use unittest.mock instead of third party mock

Now that we no longer support py27, we can use the standard library
unittest.mock module instead of the third party mock lib.

Change-Id: I7268264d3e2c98474604ec5f46298d36b7d32f18
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>
Co-Authored-By: zhurong <aaronzhu1121@gmail.com>

aodhclient/tests/unit/test_alarm_cli.py

@@ -14,8 +14,8 @@
 #    under the License.
 
 import argparse
+from unittest import mock
 
-import mock
 import testtools
 
 from aodhclient.v2 import alarm_cli

aodhclient/tests/unit/test_alarm_history.py

@@ -14,7 +14,7 @@
 #    under the License.
 
 
-import mock
+from unittest import mock
 
 import testtools
 

aodhclient/tests/unit/test_alarm_manager.py

@@ -13,8 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
 import testtools
+from unittest import mock
 
 from aodhclient.v2 import alarm
 

aodhclient/tests/unit/test_exceptions.py

@@ -12,7 +12,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import mock
+from unittest import mock
+
 from oslotest import base
 
 from aodhclient import exceptions

aodhclient/tests/unit/test_quota.py

@@ -11,8 +11,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
 import testtools
+from unittest import mock
 
 from aodhclient import exceptions
 from aodhclient.v2 import quota_cli

aodhclient/tests/unit/test_shell.py

@@ -13,9 +13,9 @@
 # under the License.
 
 import sys
+from unittest import mock
 
 from keystoneauth1 import exceptions
-import mock
 import six
 import testtools
 

setup.cfg

@@ -32,7 +32,6 @@ test =
     testtools>=1.4.0
     pifpaf[gnocchi]>=0.23
     gnocchi[postgresql,file]
-    mock>=1.2  # BSD
 
 [entry_points]
 console_scripts =