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: I436eab174b823c1e0e028529fed9009cc38776bc
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

test-requirements.txt

@@ -14,7 +14,6 @@ testrepository>=0.0.18 # Apache-2.0/BSD
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
 stestr>=1.0.0 # Apache-2.0
-mock>=2.0.0 # BSD
 
 # releasenotes
 reno>=2.5.0 # Apache-2.0

virtualbmc/tests/unit/cmd/test_vbmc.py

@@ -15,8 +15,8 @@
 
 import io
 import json
-import mock
 import sys
+from unittest import mock
 
 import zmq
 

virtualbmc/tests/unit/cmd/test_vbmcd.py

@@ -15,8 +15,8 @@
 
 import builtins
 import os
+from unittest import mock
 
-import mock
 
 from virtualbmc.cmd import vbmcd
 from virtualbmc import control

virtualbmc/tests/unit/test_config.py

@@ -15,8 +15,8 @@
 
 import configparser
 import os
+from unittest import mock
 
-import mock
 
 from virtualbmc import config
 from virtualbmc.tests.unit import base

virtualbmc/tests/unit/test_control.py

@@ -15,8 +15,8 @@
 
 import json
 import os
+from unittest import mock
 
-import mock
 
 import zmq
 

virtualbmc/tests/unit/test_manager.py

@@ -20,8 +20,8 @@ import errno
 import multiprocessing
 import os
 import shutil
+from unittest import mock
 
-import mock
 
 from virtualbmc import exception
 from virtualbmc import manager

virtualbmc/tests/unit/test_utils.py

@@ -14,9 +14,9 @@
 #    under the License.
 
 import os
+from unittest import mock
 
 import libvirt
-import mock
 
 from virtualbmc import exception
 from virtualbmc.tests.unit import base

virtualbmc/tests/unit/test_vbmc.py

@@ -14,7 +14,7 @@
 #    under the License.
 
 import libvirt
-import mock
+from unittest import mock
 
 from virtualbmc import exception
 from virtualbmc.tests.unit import base