Use "unittest.mock" library and drop "mock" installation

As commented in [1], "unittest.mock" has been supported in the Python
internal unit testing framework since version 3.3.

[1]http://lists.openstack.org/pipermail/openstack-discuss/2020-March/013281.html

Change-Id: If71241a412ecfe3471a472802e18c986bd05d5b1

doc/requirements.txt

@@ -3,4 +3,3 @@ sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4'  # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0
 os-api-ref>=1.4.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
-mock>=2.0.0 # BSD

lower-constraints.txt

@@ -28,7 +28,6 @@ linecache2==1.0.0
 Mako==0.4.0
 MarkupSafe==1.0
 mccabe==0.2.1
-mock==2.0.0
 monotonic==0.6
 mox3==0.20.0
 msgpack-python==0.4.0

neutron_lib/fixture.py

@@ -11,10 +11,10 @@
 # under the License.
 
 import copy
+from unittest import mock
 import warnings
 
 import fixtures
-import mock
 from oslo_config import cfg
 from oslo_db.sqlalchemy import enginefacade
 from oslo_db.sqlalchemy import provision

neutron_lib/tests/_base.py

@@ -17,9 +17,9 @@ import logging as std_logging
 import os
 import os.path
 import random
+from unittest import mock
 
 import fixtures
-import mock
 from oslo_config import cfg
 from oslo_db import options as db_options
 from oslo_utils import strutils

neutron_lib/tests/unit/api/test_conversions.py

@@ -13,7 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
+
 import netaddr
 import testtools
 

neutron_lib/tests/unit/api/validators/test_allowedaddresspairs.py

@@ -10,7 +10,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
+
 from oslo_config import cfg
 from webob import exc
 

neutron_lib/tests/unit/api/validators/test_availability_zone.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib.api.validators import availability_zone as az_validator
 from neutron_lib.db import constants as db_const

neutron_lib/tests/unit/api/validators/test_dns.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib.api.validators import dns
 from neutron_lib.db import constants as db_constants

neutron_lib/tests/unit/api/validators/test_validators.py

@@ -12,8 +12,8 @@
 #    under the License.
 
 import string
+from unittest import mock
 
-import mock
 import netaddr
 
 from neutron_lib._i18n import _

neutron_lib/tests/unit/callbacks/test_events.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib.callbacks import events
 from oslotest import base

neutron_lib/tests/unit/callbacks/test_manager.py

@@ -12,7 +12,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from oslo_db import exception as db_exc
 from oslotest import base

neutron_lib/tests/unit/callbacks/test_registry.py

@@ -12,10 +12,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
-import testtools
+from unittest import mock
 
 from oslotest import base
+import testtools
 
 from neutron_lib.callbacks import events
 from neutron_lib.callbacks import priority_group

neutron_lib/tests/unit/db/test_api.py

@@ -11,7 +11,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
+from unittest import mock
+
 from oslo_db import exception as db_exc
 import osprofiler
 import sqlalchemy

neutron_lib/tests/unit/db/test_model_query.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib.db import model_query
 from neutron_lib import fixture

neutron_lib/tests/unit/db/test_utils.py

@@ -10,7 +10,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import mock
+from unittest import mock
 
 from oslo_db.sqlalchemy import models
 import sqlalchemy as sa

neutron_lib/tests/unit/objects/test_utils.py

@@ -10,7 +10,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib.objects import utils as obj_utils
 from neutron_lib.tests import _base as base

neutron_lib/tests/unit/placement/test_client.py

@@ -11,7 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
+from unittest import mock
 
 from keystoneauth1 import exceptions as ks_exc
 from keystoneauth1 import loading as keystone

neutron_lib/tests/unit/plugins/test_utils.py

@@ -13,8 +13,8 @@
 #    under the License.
 
 import hashlib
+from unittest import mock
 
-import mock
 from oslo_utils import excutils
 from oslo_utils import uuidutils
 

neutron_lib/tests/unit/policy/test__engine.py

@@ -11,7 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib import context
 from neutron_lib.policy import _engine as policy_engine

neutron_lib/tests/unit/services/qos/test_base.py

@@ -12,7 +12,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib.api.definitions import portbindings
 from neutron_lib import constants

neutron_lib/tests/unit/test_context.py

@@ -10,7 +10,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
+
 from oslo_context import context as oslo_context
 from testtools import matchers
 

neutron_lib/tests/unit/test_fixture.py

@@ -11,8 +11,8 @@
 # under the License.
 
 import re
+from unittest import mock
 
-import mock
 from oslo_config import cfg
 from oslo_db import options
 from oslotest import base

neutron_lib/tests/unit/test_rpc.py

@@ -10,7 +10,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import mock
+from unittest import mock
 
 from oslo_config import cfg
 import oslo_messaging as messaging

neutron_lib/tests/unit/test_worker.py

@@ -12,7 +12,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import mock
+from unittest import mock
 
 from neutron_lib.callbacks import events
 from neutron_lib.callbacks import resources

neutron_lib/tests/unit/utils/test_host.py

@@ -12,8 +12,7 @@
 # limitations under the License.
 
 import multiprocessing
-
-import mock
+from unittest import mock
 
 from neutron_lib.tests import _base as base
 from neutron_lib.utils import host

neutron_lib/tests/unit/utils/test_net.py

@@ -14,8 +14,7 @@
 import itertools
 import random
 import socket
-
-import mock
+from unittest import mock
 
 from neutron_lib import constants
 from neutron_lib.tests import _base as base

neutron_lib/tests/unit/utils/test_runtime.py

@@ -11,7 +11,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
+from unittest import mock
+
 from stevedore import enabled
 
 from neutron_lib.tests import _base as base