Use standard library unittest.mock instead of mock

Use unittest.mock instead of mock.
Because mock became part of standard library
and available as unittest.mock since Python 3.6

Change-Id: Ibfe27316c20fa2c8935b559fed7885a6e194d314

scciclient/tests/irmc/test_elcm.py

@@ -16,7 +16,8 @@
 Test class for iRMC eLCM functionality.
 """
 
-import mock
+from unittest import mock
+
 from oslo_utils import encodeutils
 import requests
 from requests_mock.contrib import fixture as rm_fixture

scciclient/tests/irmc/test_ipmi.py

@@ -15,7 +15,8 @@
 Test class for IPMI Module.
 """
 
-import mock
+from unittest import mock
+
 from pyghmi import exceptions as ipmi_exception
 from pyghmi.ipmi import command as ipmi_command
 import testtools

scciclient/tests/irmc/test_scci.py

@@ -17,10 +17,10 @@ Test class for iRMC Power Driver
 
 import os
 import time
+from unittest import mock
 import xml.etree.ElementTree as ET
 
 import defusedxml.ElementTree as dET
-import mock
 from requests_mock.contrib import fixture as rm_fixture
 import six
 import six.moves.builtins as __builtin__

scciclient/tests/irmc/test_snmp.py

@@ -15,8 +15,8 @@
 Test class for snmp module.
 """
 
+from unittest import mock
 
-import mock
 from pysnmp.entity.rfc3413.oneliner import cmdgen
 from pysnmp import error as snmp_error
 import testtools

scciclient/tests/irmc/viom/test_client.py

@@ -12,7 +12,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import mock
+from unittest import mock
+
 import testtools
 
 from scciclient.irmc import scci

scciclient/tests/irmc/viom/test_elcm.py

@@ -17,8 +17,8 @@ Test class for iRMC eLCM functionality.
 """
 
 import time
+from unittest import mock
 
-import mock
 import testtools
 
 from scciclient.irmc import elcm

test-requirements.txt

@@ -4,7 +4,6 @@
 
 coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
-mock>=2.0.0 # BSD
 python-subunit>=1.0.0 # Apache-2.0/BSD
 oslotest>=3.2.0,<4;python_version<'3.6'  # Apache-2.0
 oslotest>=3.2.0;python_version>='3.6'  # Apache-2.0