Remove double mocking... again

I thought we fixed all the double mocking issues with
I3998d0d49583806ac1c3ae64f1b1fe343cefd20d but I was wrong.

While we used both mock and unittest.mock the fixtures.MockPatch
used the mock lib instead of the unittest.mock lib.
The path Ibf4f36136f2c65adad64f75d665c00cf2de4b400 (Remove the PowerVM driver)
removed the last user of mock lib from nova. So it is also
removed the mock from test-requirements. This triggered that
fixtures.MockPatch athat started using unittest.mock too.

Before Ibf4f36136f2c65adad64f75d665c00cf2de4b400 a function can be mocked
twice once with unittest.mock and once with fixtures.MockPatch (still
using mock). However after that patch both path of such double
mocking goes through unittest.mock and the second one fails.

So this patch fixes double mocking so far hidden behind
fixtures.MockPatch.

This patch made the py310 and functional-py310 jobs voting  on master
however that has been dropped as part of the backport.

Conflicts:
    nova/tests/fixtures/nova.py
    nova/tests/unit/api/openstack/compute/test_quotas.py
    nova/tests/unit/api/openstack/compute/test_server_group_quotas.py

Conflicts are due to lack of unified limits feature in xena

Change-Id: Ic1352ec31996577a5d0ad18a057339df3e49de25
(cherry picked from commit bf654e3a4a8f690ad0bec0955690bf4fadf98dba)
(cherry picked from commit 69667a817cb65c3efbe4e3ada0e8c69c0a106087)

20 files changed, 158 insertions, 187 deletions

diff --git a/nova/tests/fixtures/libvirt.py b/nova/tests/fixtures/libvirt.py
index 031ddcb53f..a05dc4378a 100644
--- a/nova/tests/fixtures/libvirt.py
+++ b/nova/tests/fixtures/libvirt.py
@@ -2180,8 +2180,8 @@ class LibvirtFixture(fixtures.Fixture):
 
         self.useFixture(
             fixtures.MockPatch('nova.virt.libvirt.utils.get_fs_info'))
-        self.useFixture(
-            fixtures.MockPatch('nova.compute.utils.get_machine_ips'))
+        self.mock_get_machine_ips = self.useFixture(
+            fixtures.MockPatch('nova.compute.utils.get_machine_ips')).mock
 
         # libvirt driver needs to call out to the filesystem to get the
         # parent_ifname for the SRIOV VFs.
@@ -2191,20 +2191,25 @@ class LibvirtFixture(fixtures.Fixture):
 
         self.useFixture(fixtures.MockPatch(
             'nova.pci.utils.get_mac_by_pci_address',
-            new=self.fake_get_mac_by_pci_address))
+            side_effect=self.fake_get_mac_by_pci_address))
 
         # libvirt calls out to sysfs to get the vfs ID during macvtap plug
-        self.useFixture(fixtures.MockPatch(
-            'nova.pci.utils.get_vf_num_by_pci_address', return_value=1))
+        self.mock_get_vf_num_by_pci_address = self.useFixture(
+            fixtures.MockPatch(
+                'nova.pci.utils.get_vf_num_by_pci_address', return_value=1
+            )
+        ).mock
 
         # libvirt calls out to privsep to set the mac and vlan of a macvtap
-        self.useFixture(fixtures.MockPatch(
-            'nova.privsep.linux_net.set_device_macaddr_and_vlan'))
+        self.mock_set_device_macaddr_and_vlan = self.useFixture(
+            fixtures.MockPatch(
+                'nova.privsep.linux_net.set_device_macaddr_and_vlan')).mock
 
         # libvirt calls out to privsep to set the port state during macvtap
         # plug
-        self.useFixture(fixtures.MockPatch(
-            'nova.privsep.linux_net.set_device_macaddr'))
+        self.mock_set_device_macaddr = self.useFixture(
+            fixtures.MockPatch(
+                'nova.privsep.linux_net.set_device_macaddr')).mock
 
         # Don't assume that the system running tests has a valid machine-id
         self.useFixture(fixtures.MockPatch(
@@ -2219,8 +2224,8 @@ class LibvirtFixture(fixtures.Fixture):
         # Ensure tests perform the same on all host architectures
         fake_uname = os_uname(
             'Linux', '', '5.4.0-0-generic', '', obj_fields.Architecture.X86_64)
-        self.useFixture(
-            fixtures.MockPatch('os.uname', return_value=fake_uname))
+        self.mock_uname = self.useFixture(
+            fixtures.MockPatch('os.uname', return_value=fake_uname)).mock
 
         # ...and on all machine types
         fake_loaders = [
diff --git a/nova/tests/fixtures/nova.py b/nova/tests/fixtures/nova.py
index 8294f9f99d..f8f4cc89f9 100644
--- a/nova/tests/fixtures/nova.py
+++ b/nova/tests/fixtures/nova.py
@@ -949,9 +949,18 @@ class OSAPIFixture(fixtures.Fixture):
             base_url += '/' + self.project_id
 
         self.api = client.TestOpenStackClient(
-            'fake', base_url, project_id=self.project_id)
+            'fake', base_url, project_id=self.project_id,
+        )
+        self.alternative_api = client.TestOpenStackClient(
+            'fake', base_url, project_id=self.project_id,
+        )
         self.admin_api = client.TestOpenStackClient(
-            'admin', base_url, project_id=self.project_id)
+            'admin', base_url, project_id=self.project_id,
+        )
+        self.alternative_admin_api = client.TestOpenStackClient(
+            'admin', base_url, project_id=self.project_id,
+        )
+
         # Provide a way to access the wsgi application to tests using
         # the fixture.
         self.app = app
@@ -1039,9 +1048,9 @@ class PoisonFunctions(fixtures.Fixture):
         # Don't poison the function if it's already mocked
         import nova.virt.libvirt.host
         if not isinstance(nova.virt.libvirt.host.Host._init_events, mock.Mock):
-            self.useFixture(fixtures.MockPatch(
+            self.useFixture(fixtures.MonkeyPatch(
                 'nova.virt.libvirt.host.Host._init_events',
-                side_effect=evloop))
+                evloop))
 
 
 class IndirectionAPIFixture(fixtures.Fixture):
diff --git a/nova/tests/functional/compute/test_resource_tracker.py b/nova/tests/functional/compute/test_resource_tracker.py
index 81b7dfb68c..758c15f371 100644
--- a/nova/tests/functional/compute/test_resource_tracker.py
+++ b/nova/tests/functional/compute/test_resource_tracker.py
@@ -29,7 +29,6 @@ from nova import conf
 from nova import context
 from nova import objects
 from nova import test
-from nova.tests import fixtures as nova_fixtures
 from nova.tests.functional import fixtures as func_fixtures
 from nova.tests.functional import integrated_helpers
 from nova.virt import driver as virt_driver
@@ -694,15 +693,6 @@ class TestProviderConfig(integrated_helpers.ProviderUsageBaseTestCase):
         feature a vm cannot be spawning using a custom trait and then start a
         compute service that provides that trait.
         """
-
-        self.useFixture(nova_fixtures.NeutronFixture(self))
-        self.useFixture(nova_fixtures.GlanceFixture(self))
-
-        # Start nova services.
-        self.api = self.useFixture(nova_fixtures.OSAPIFixture(
-            api_version='v2.1')).admin_api
-        self.api.microversion = 'latest'
-        self.start_service('conductor')
         # start nova-compute that will not have the additional trait.
         self._start_compute("fake-host-1")
 
diff --git a/nova/tests/functional/libvirt/base.py b/nova/tests/functional/libvirt/base.py
index 8aefb0a694..018e4d6f38 100644
--- a/nova/tests/functional/libvirt/base.py
+++ b/nova/tests/functional/libvirt/base.py
@@ -51,12 +51,12 @@ class ServersTestBase(integrated_helpers._IntegratedTestBase):
         self.useFixture(fixtures.MockPatch(
             'nova.virt.libvirt.LibvirtDriver._get_local_gb_info',
             return_value={'total': 128, 'used': 44, 'free': 84}))
-        self.useFixture(fixtures.MockPatch(
+        self.mock_is_valid_hostname = self.useFixture(fixtures.MockPatch(
             'nova.virt.libvirt.driver.libvirt_utils.is_valid_hostname',
-            return_value=True))
-        self.useFixture(fixtures.MockPatch(
+            return_value=True)).mock
+        self.mock_file_open = self.useFixture(fixtures.MockPatch(
             'nova.virt.libvirt.driver.libvirt_utils.file_open',
-            side_effect=lambda *a, **k: io.BytesIO(b'')))
+            side_effect=lambda *a, **k: io.BytesIO(b''))).mock
         self.useFixture(fixtures.MockPatch(
             'nova.privsep.utils.supports_direct_io',
             return_value=True))
diff --git a/nova/tests/functional/libvirt/test_reshape.py b/nova/tests/functional/libvirt/test_reshape.py
index 5c73ffbf5f..8249100111 100644
--- a/nova/tests/functional/libvirt/test_reshape.py
+++ b/nova/tests/functional/libvirt/test_reshape.py
@@ -30,17 +30,7 @@ LOG = logging.getLogger(__name__)
 
 class VGPUReshapeTests(base.ServersTestBase):
 
-    @mock.patch('nova.virt.libvirt.LibvirtDriver._get_local_gb_info',
-                return_value={'total': 128,
-                              'used': 44,
-                              'free': 84})
-    @mock.patch('nova.virt.libvirt.driver.libvirt_utils.is_valid_hostname',
-                return_value=True)
-    @mock.patch('nova.virt.libvirt.driver.libvirt_utils.file_open',
-                side_effect=[io.BytesIO(b''), io.BytesIO(b''),
-                             io.BytesIO(b'')])
-    def test_create_servers_with_vgpu(
-            self, mock_file_open, mock_valid_hostname, mock_get_fs_info):
+    def test_create_servers_with_vgpu(self):
         """Verify that vgpu reshape works with libvirt driver
 
         1) create two servers with an old tree where the VGPU resource is on
@@ -49,7 +39,8 @@ class VGPUReshapeTests(base.ServersTestBase):
         3) check that the allocations of the servers are still valid
         4) create another server now against the new tree
         """
-
+        self.mock_file_open.side_effect = [
+            io.BytesIO(b''), io.BytesIO(b''), io.BytesIO(b'')]
         # NOTE(gibi): We cannot simply ask the virt driver to create an old
         # RP tree with vgpu on the root RP as that code path does not exist
         # any more. So we have to hack a "bit". We will create a compute
diff --git a/nova/tests/functional/libvirt/test_vgpu.py b/nova/tests/functional/libvirt/test_vgpu.py
index f25ce44221..e111f50de0 100644
--- a/nova/tests/functional/libvirt/test_vgpu.py
+++ b/nova/tests/functional/libvirt/test_vgpu.py
@@ -49,11 +49,11 @@ class VGPUTestBase(base.ServersTestBase):
 
     def setUp(self):
         super(VGPUTestBase, self).setUp()
-        self.useFixture(fixtures.MockPatch(
-            'nova.virt.libvirt.LibvirtDriver._get_local_gb_info',
-            return_value={'total': 128,
-                          'used': 44,
-                          'free': 84}))
+        libvirt_driver.LibvirtDriver._get_local_gb_info.return_value = {
+            'total': 128,
+            'used': 44,
+            'free': 84,
+        }
         self.useFixture(fixtures.MockPatch(
             'nova.privsep.libvirt.create_mdev',
             side_effect=self._create_mdev))
diff --git a/nova/tests/functional/test_aggregates.py b/nova/tests/functional/test_aggregates.py
index 508c435f54..b7aabdc3d8 100644
--- a/nova/tests/functional/test_aggregates.py
+++ b/nova/tests/functional/test_aggregates.py
@@ -826,11 +826,11 @@ class TestAggregateMultiTenancyIsolationFilter(
 
         # Start nova services.
         self.start_service('conductor')
-        self.admin_api = self.useFixture(
-            nova_fixtures.OSAPIFixture(api_version='v2.1')).admin_api
-        self.api = self.useFixture(
-            nova_fixtures.OSAPIFixture(api_version='v2.1',
-                                       project_id=uuids.non_admin)).api
+        api_fixture = self.useFixture(
+            nova_fixtures.OSAPIFixture(api_version='v2.1'))
+        self.admin_api = api_fixture.admin_api
+        self.api = api_fixture.api
+        self.api.project_id = uuids.non_admin
         # Add the AggregateMultiTenancyIsolation to the list of enabled
         # filters since it is not enabled by default.
         enabled_filters = CONF.filter_scheduler.enabled_filters
@@ -928,15 +928,15 @@ class AggregateMultiTenancyIsolationColdMigrateTest(
         self.glance = self.useFixture(nova_fixtures.GlanceFixture(self))
         self.useFixture(nova_fixtures.NeutronFixture(self))
         self.useFixture(func_fixtures.PlacementFixture())
-        # Intentionally keep these separate since we want to create the
-        # server with the non-admin user in a different project.
-        admin_api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
+        # Intentionally define different project id for the two client since
+        # we want to create the server with the non-admin user in a different
+        # project.
+        api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1', project_id=uuids.admin_project))
-        self.admin_api = admin_api_fixture.admin_api
+        self.admin_api = api_fixture.admin_api
         self.admin_api.microversion = 'latest'
-        user_api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
-            api_version='v2.1', project_id=uuids.user_project))
-        self.api = user_api_fixture.api
+        self.api = api_fixture.api
+        self.api.project_id = uuids.user_project
         self.api.microversion = 'latest'
 
         self.start_service('conductor')
diff --git a/nova/tests/functional/test_images.py b/nova/tests/functional/test_images.py
index 340e883da9..e7e9f2a6c9 100644
--- a/nova/tests/functional/test_images.py
+++ b/nova/tests/functional/test_images.py
@@ -12,7 +12,6 @@
 
 from oslo_utils.fixture import uuidsentinel as uuids
 
-from nova.tests import fixtures as nova_fixtures
 from nova.tests.functional.api import client
 from nova.tests.functional import integrated_helpers
 
@@ -70,10 +69,9 @@ class ImagesTest(integrated_helpers._IntegratedTestBase):
         server = self.api.post_server({"server": server})
         server = self._wait_for_state_change(server, 'ACTIVE')
 
-        # Create an admin API fixture with a unique project ID.
-        admin_api = self.useFixture(
-            nova_fixtures.OSAPIFixture(
-                project_id=uuids.admin_project)).admin_api
+        # use an admin API with a unique project ID.
+        admin_api = self.api_fixture.alternative_admin_api
+        admin_api.project_id = uuids.admin_project
 
         # Create a snapshot of the server using the admin project.
         name = 'admin-created-snapshot'
diff --git a/nova/tests/functional/test_server_group.py b/nova/tests/functional/test_server_group.py
index 08e47b3971..a64a04b2c9 100644
--- a/nova/tests/functional/test_server_group.py
+++ b/nova/tests/functional/test_server_group.py
@@ -64,12 +64,12 @@ class ServerGroupTestBase(test.TestCase,
         self.useFixture(nova_fixtures.NeutronFixture(self))
 
         self.useFixture(func_fixtures.PlacementFixture())
-        api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
+        self.api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
             api_version='v2.1'))
 
-        self.api = api_fixture.api
+        self.api = self.api_fixture.api
         self.api.microversion = self.microversion
-        self.admin_api = api_fixture.admin_api
+        self.admin_api = self.api_fixture.admin_api
         self.admin_api.microversion = self.microversion
 
         self.start_service('conductor')
@@ -174,13 +174,8 @@ class ServerGroupTestV21(ServerGroupTestBase):
 
         # Create an API using project 'openstack1'.
         # This is a non-admin API.
-        #
-        # NOTE(sdague): this is actually very much *not* how this
-        # fixture should be used. This actually spawns a whole
-        # additional API server. Should be addressed in the future.
-        api_openstack1 = self.useFixture(nova_fixtures.OSAPIFixture(
-            api_version=self.api_major_version,
-            project_id=PROJECT_ID_ALT)).api
+        api_openstack1 = self.api_fixture.alternative_api
+        api_openstack1.project_id = PROJECT_ID_ALT
         api_openstack1.microversion = self.microversion
 
         # Create a server group in project 'openstack'
diff --git a/nova/tests/functional/test_servers.py b/nova/tests/functional/test_servers.py
index 117bbe8a41..9f4d8bb893 100644
--- a/nova/tests/functional/test_servers.py
+++ b/nova/tests/functional/test_servers.py
@@ -1253,9 +1253,7 @@ class ServerTestV269(integrated_helpers._IntegratedTestBase):
     def test_get_servers_detail_filters(self):
         # We get the results only from the up cells, this ignoring the down
         # cells if list_records_by_skipping_down_cells config option is True.
-        api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
-            api_version='v2.1'))
-        self.admin_api = api_fixture.admin_api
+        self.admin_api = self.api_fixture.admin_api
         self.admin_api.microversion = '2.69'
         servers = self.admin_api.get_servers(
             search_opts={'hostname': "cell3-inst0"})
@@ -1263,9 +1261,7 @@ class ServerTestV269(integrated_helpers._IntegratedTestBase):
         self.assertEqual(self.up_cell_insts[2], servers[0]['id'])
 
     def test_get_servers_detail_all_tenants_with_down_cells(self):
-        api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
-            api_version='v2.1'))
-        self.admin_api = api_fixture.admin_api
+        self.admin_api = self.api_fixture.admin_api
         self.admin_api.microversion = '2.69'
         servers = self.admin_api.get_servers(search_opts={'all_tenants': True})
         # 4 servers from the up cells and 4 servers from the down cells
@@ -1523,10 +1519,8 @@ class ServersTestV280(integrated_helpers._IntegratedTestBase):
 
     def setUp(self):
         super(ServersTestV280, self).setUp()
-        api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
-            api_version='v2.1'))
-        self.api = api_fixture.api
-        self.admin_api = api_fixture.admin_api
+        self.api = self.api_fixture.api
+        self.admin_api = self.api_fixture.admin_api
 
         self.api.microversion = '2.80'
         self.admin_api.microversion = '2.80'
@@ -1585,9 +1579,8 @@ class ServersTestV280(integrated_helpers._IntegratedTestBase):
 
         project_id_1 = '4906260553374bf0a5d566543b320516'
         project_id_2 = 'c850298c1b6b4796a8f197ac310b2469'
-        new_api_fixture = self.useFixture(nova_fixtures.OSAPIFixture(
-            api_version=self.api_major_version, project_id=project_id_1))
-        new_admin_api = new_api_fixture.admin_api
+        new_admin_api = self.api_fixture.alternative_admin_api
+        new_admin_api.project_id = project_id_1
         new_admin_api.microversion = '2.80'
 
         post = {
diff --git a/nova/tests/unit/api/openstack/compute/test_create_backup.py b/nova/tests/unit/api/openstack/compute/test_create_backup.py
index f7280a5a37..70978d11de 100644
--- a/nova/tests/unit/api/openstack/compute/test_create_backup.py
+++ b/nova/tests/unit/api/openstack/compute/test_create_backup.py
@@ -40,10 +40,6 @@ class CreateBackupTestsV21(admin_only_action_common.CommonMixin,
         self.controller = getattr(self.create_backup, self.controller_name)()
         self.compute_api = self.controller.compute_api
 
-        patch_get = mock.patch.object(self.compute_api, 'get')
-        self.mock_get = patch_get.start()
-        self.addCleanup(patch_get.stop)
-
     @mock.patch.object(common, 'check_img_metadata_properties_quota')
     @mock.patch.object(api.API, 'backup')
     def test_create_backup_with_metadata(self, mock_backup, mock_check_image):
diff --git a/nova/tests/unit/api/openstack/compute/test_migrate_server.py b/nova/tests/unit/api/openstack/compute/test_migrate_server.py
index 683759eccc..325b4927b3 100644
--- a/nova/tests/unit/api/openstack/compute/test_migrate_server.py
+++ b/nova/tests/unit/api/openstack/compute/test_migrate_server.py
@@ -530,9 +530,8 @@ class MigrateServerTestsV256(MigrateServerTestsV234):
                           self.req, fakes.FAKE_UUID, body=body)
 
     def _test_migrate_exception(self, exc_info, expected_result):
-        @mock.patch.object(self.compute_api, 'get')
         @mock.patch.object(self.compute_api, 'resize', side_effect=exc_info)
-        def _test(mock_resize, mock_get):
+        def _test(mock_resize):
             instance = objects.Instance(uuid=uuids.instance)
             self.assertRaises(expected_result,
                               self.controller._migrate,
diff --git a/nova/tests/unit/api/openstack/compute/test_servers.py b/nova/tests/unit/api/openstack/compute/test_servers.py
index 28a4865577..d44f404559 100644
--- a/nova/tests/unit/api/openstack/compute/test_servers.py
+++ b/nova/tests/unit/api/openstack/compute/test_servers.py
@@ -2087,10 +2087,10 @@ class ServersControllerTestV216(_ServersControllerTest):
 
         return server_dict
 
-    @mock.patch('nova.compute.api.API.get_instance_host_status')
-    def _verify_host_status_policy_behavior(self, func, mock_get_host_status):
+    def _verify_host_status_policy_behavior(self, func):
         # Set policy to disallow both host_status cases and verify we don't
         # call the get_instance_host_status compute RPC API.
+        self.mock_get_instance_host_status.reset_mock()
         rules = {
             'os_compute_api:servers:show:host_status': '!',
             'os_compute_api:servers:show:host_status:unknown-only': '!',
@@ -2098,7 +2098,7 @@ class ServersControllerTestV216(_ServersControllerTest):
         orig_rules = policy.get_rules()
         policy.set_rules(oslo_policy.Rules.from_dict(rules), overwrite=False)
         func()
-        mock_get_host_status.assert_not_called()
+        self.mock_get_instance_host_status.assert_not_called()
         # Restore the original rules.
         policy.set_rules(orig_rules)
 
@@ -2638,15 +2638,13 @@ class ServersControllerTestV275(ControllerTest):
 
     microversion = '2.75'
 
-    @mock.patch('nova.compute.api.API.get_all')
-    def test_get_servers_additional_query_param_old_version(self, mock_get):
+    def test_get_servers_additional_query_param_old_version(self):
         req = fakes.HTTPRequest.blank(self.path_with_query % 'unknown=1',
                                       use_admin_context=True,
                                       version='2.74')
         self.controller.index(req)
 
-    @mock.patch('nova.compute.api.API.get_all')
-    def test_get_servers_ignore_sort_key_old_version(self, mock_get):
+    def test_get_servers_ignore_sort_key_old_version(self):
         req = fakes.HTTPRequest.blank(
                 self.path_with_query % 'sort_key=deleted',
                 use_admin_context=True, version='2.74')
@@ -3584,13 +3582,13 @@ class ServersControllerRebuildTestV263(ControllerTest):
             },
         }
 
-    @mock.patch('nova.compute.api.API.get')
-    def _rebuild_server(self, mock_get, certs=None,
-                        conf_enabled=True, conf_certs=None):
+    def _rebuild_server(self, certs=None, conf_enabled=True, conf_certs=None):
         ctx = self.req.environ['nova.context']
-        mock_get.return_value = fakes.stub_instance_obj(ctx,
-            vm_state=vm_states.ACTIVE, trusted_certs=certs,
-            project_id=self.req_project_id, user_id=self.req_user_id)
+        self.mock_get.side_effect = None
+        self.mock_get.return_value = fakes.stub_instance_obj(
+            ctx, vm_state=vm_states.ACTIVE, trusted_certs=certs,
+            project_id=self.req_project_id, user_id=self.req_user_id
+        )
 
         self.flags(default_trusted_certificate_ids=conf_certs, group='glance')
 
@@ -3743,10 +3741,10 @@ class ServersControllerRebuildTestV271(ControllerTest):
             }
         }
 
-    @mock.patch('nova.compute.api.API.get')
-    def _rebuild_server(self, mock_get):
+    def _rebuild_server(self):
         ctx = self.req.environ['nova.context']
-        mock_get.return_value = fakes.stub_instance_obj(ctx,
+        self.mock_get.side_effect = None
+        self.mock_get.return_value = fakes.stub_instance_obj(ctx,
             vm_state=vm_states.ACTIVE, project_id=self.req_project_id,
             user_id=self.req_user_id)
         server = self.controller._action_rebuild(
diff --git a/nova/tests/unit/api/openstack/compute/test_volumes.py b/nova/tests/unit/api/openstack/compute/test_volumes.py
index 78a37934c4..c0173aad9d 100644
--- a/nova/tests/unit/api/openstack/compute/test_volumes.py
+++ b/nova/tests/unit/api/openstack/compute/test_volumes.py
@@ -1888,8 +1888,7 @@ class AssistedSnapshotDeleteTestCaseV21(test.NoDBTestCase):
                 req, '5')
 
     def _test_assisted_delete_instance_conflict(self, api_error):
-        # unset the stub on volume_snapshot_delete from setUp
-        self.mock_volume_snapshot_delete.stop()
+        self.mock_volume_snapshot_delete.side_effect = api_error
         params = {
             'delete_info': jsonutils.dumps({'volume_id': '1'}),
         }
@@ -1898,10 +1897,9 @@ class AssistedSnapshotDeleteTestCaseV21(test.NoDBTestCase):
                 urllib.parse.urlencode(params),
                 version=self.microversion)
         req.method = 'DELETE'
-        with mock.patch.object(compute_api.API, 'volume_snapshot_delete',
-                               side_effect=api_error):
-            self.assertRaises(
-                webob.exc.HTTPBadRequest, self.controller.delete, req, '5')
+
+        self.assertRaises(
+            webob.exc.HTTPBadRequest, self.controller.delete, req, '5')
 
     def test_assisted_delete_instance_invalid_state(self):
         api_error = exception.InstanceInvalidState(
diff --git a/nova/tests/unit/compute/test_api.py b/nova/tests/unit/compute/test_api.py
index 81eed9988d..9f0b0a98ca 100644
--- a/nova/tests/unit/compute/test_api.py
+++ b/nova/tests/unit/compute/test_api.py
@@ -961,6 +961,31 @@ class _ComputeAPIUnitTestMixIn(object):
 
         return snapshot_id
 
+    def _test_delete(self, delete_type, **attrs):
+        delete_time = datetime.datetime(
+            1955, 11, 5, 9, 30, tzinfo=iso8601.UTC)
+        timeutils.set_time_override(delete_time)
+        self.addCleanup(timeutils.clear_time_override)
+
+        with test.nested(
+            mock.patch.object(
+                self.compute_api.compute_rpcapi, 'confirm_resize'),
+            mock.patch.object(
+                self.compute_api.compute_rpcapi, 'terminate_instance'),
+            mock.patch.object(
+                self.compute_api.compute_rpcapi, 'soft_delete_instance'),
+        ) as (
+            mock_confirm, mock_terminate, mock_soft_delete
+        ):
+            self._do_delete(
+                delete_type,
+                mock_confirm,
+                mock_terminate,
+                mock_soft_delete,
+                delete_time,
+                **attrs
+            )
+
     @mock.patch.object(compute_utils,
                        'notify_about_instance_action')
     @mock.patch.object(objects.Migration, 'get_by_instance_and_status')
@@ -980,12 +1005,13 @@ class _ComputeAPIUnitTestMixIn(object):
     @mock.patch.object(objects.BlockDeviceMappingList,
                        'get_by_instance_uuid', return_value=[])
     @mock.patch.object(objects.Instance, 'save')
-    def _test_delete(self, delete_type, mock_save, mock_bdm_get, mock_elevated,
-                     mock_get_cn, mock_up, mock_record, mock_inst_update,
-                     mock_deallocate, mock_inst_meta, mock_inst_destroy,
-                     mock_notify_legacy, mock_get_inst,
-                     mock_save_im, mock_image_delete, mock_mig_get,
-                     mock_notify, **attrs):
+    def _do_delete(
+        self, delete_type, mock_confirm, mock_terminate, mock_soft_delete,
+        delete_time, mock_save, mock_bdm_get, mock_elevated, mock_get_cn,
+        mock_up, mock_record, mock_inst_update, mock_deallocate,
+        mock_inst_meta, mock_inst_destroy, mock_notify_legacy, mock_get_inst,
+        mock_save_im, mock_image_delete, mock_mig_get, mock_notify, **attrs
+    ):
         expected_save_calls = [mock.call()]
         expected_record_calls = []
         expected_elevated_calls = []
@@ -995,17 +1021,11 @@ class _ComputeAPIUnitTestMixIn(object):
         deltas = {'instances': -1,
                   'cores': -inst.flavor.vcpus,
                   'ram': -inst.flavor.memory_mb}
-        delete_time = datetime.datetime(1955, 11, 5, 9, 30,
-                                        tzinfo=iso8601.UTC)
-        self.useFixture(utils_fixture.TimeFixture(delete_time))
         task_state = (delete_type == 'soft_delete' and
                       task_states.SOFT_DELETING or task_states.DELETING)
         updates = {'progress': 0, 'task_state': task_state}
         if delete_type == 'soft_delete':
             updates['deleted_at'] = delete_time
-        rpcapi = self.compute_api.compute_rpcapi
-        mock_confirm = self.useFixture(
-            fixtures.MockPatchObject(rpcapi, 'confirm_resize')).mock
 
         def _reset_task_state(context, instance, migration, src_host,
                               cast=False):
@@ -1020,11 +1040,6 @@ class _ComputeAPIUnitTestMixIn(object):
             snapshot_id = self._set_delete_shelved_part(inst,
                                                         mock_image_delete)
 
-        mock_terminate = self.useFixture(
-            fixtures.MockPatchObject(rpcapi, 'terminate_instance')).mock
-        mock_soft_delete = self.useFixture(
-            fixtures.MockPatchObject(rpcapi, 'soft_delete_instance')).mock
-
         if inst.task_state == task_states.RESIZE_FINISH:
             self._test_delete_resizing_part(inst, deltas)
 
@@ -2595,9 +2610,6 @@ class _ComputeAPIUnitTestMixIn(object):
 
         rpcapi = self.compute_api.compute_rpcapi
 
-        mock_pause = self.useFixture(
-            fixtures.MockPatchObject(rpcapi, 'pause_instance')).mock
-
         with mock.patch.object(rpcapi, 'pause_instance') as mock_pause:
             self.compute_api.pause(self.context, instance)
 
diff --git a/nova/tests/unit/policies/test_servers.py b/nova/tests/unit/policies/test_servers.py
index 33aadb948f..0b98959c49 100644
--- a/nova/tests/unit/policies/test_servers.py
+++ b/nova/tests/unit/policies/test_servers.py
@@ -1230,10 +1230,9 @@ class ServersPolicyTest(base.BasePolicyTest):
     @mock.patch('nova.compute.api.API._allow_resize_to_same_host')
     @mock.patch('nova.objects.RequestSpec.get_by_instance_uuid')
     @mock.patch('nova.objects.Instance.save')
-    @mock.patch('nova.api.openstack.common.get_instance')
     @mock.patch('nova.conductor.ComputeTaskAPI.resize_instance')
     def test_cross_cell_resize_server_policy(
-        self, mock_resize, mock_get, mock_save, mock_rs, mock_allow, m_net
+        self, mock_resize, mock_save, mock_rs, mock_allow, m_net
     ):
 
         # 'migrate' policy is checked before 'resize:cross_cell' so
@@ -1263,7 +1262,7 @@ class ServersPolicyTest(base.BasePolicyTest):
             )
             return inst
 
-        mock_get.side_effect = fake_get
+        self.mock_get.side_effect = fake_get
 
         def fake_validate(context, instance,
             host_name, allow_cross_cell_resize):
diff --git a/nova/tests/unit/virt/ironic/test_driver.py b/nova/tests/unit/virt/ironic/test_driver.py
index 7b377b21c2..0b1cc7d47f 100644
--- a/nova/tests/unit/virt/ironic/test_driver.py
+++ b/nova/tests/unit/virt/ironic/test_driver.py
@@ -2597,9 +2597,6 @@ class IronicDriverSyncTestCase(IronicDriverTestCase):
         # that the thread completes.
         self.useFixture(nova_fixtures.SpawnIsSynchronousFixture())
 
-        self.mock_conn = self.useFixture(
-            fixtures.MockPatchObject(self.driver, '_ironic_connection')).mock
-
     @mock.patch.object(loopingcall, 'FixedIntervalLoopingCall')
     @mock.patch.object(FAKE_CLIENT.node, 'set_provision_state')
     def test_rescue(self, mock_sps, mock_looping):
diff --git a/nova/tests/unit/virt/libvirt/test_driver.py b/nova/tests/unit/virt/libvirt/test_driver.py
index 51028595cb..224b36f5c7 100644
--- a/nova/tests/unit/virt/libvirt/test_driver.py
+++ b/nova/tests/unit/virt/libvirt/test_driver.py
@@ -740,16 +740,14 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                       'resolve_driver_format',
                       imagebackend.Image._get_driver_format)
 
-        self.useFixture(nova_fixtures.LibvirtFixture())
+        self.libvirt = self.useFixture(nova_fixtures.LibvirtFixture())
 
         # ensure tests perform the same on all host architectures; this is
         # already done by the fakelibvirt fixture but we want to change the
         # architecture in some tests
-        _p = mock.patch('os.uname')
-        self.mock_uname = _p.start()
+        self.mock_uname = self.libvirt.mock_uname
         self.mock_uname.return_value = fakelibvirt.os_uname(
             'Linux', '', '5.4.0-0-generic', '', fields.Architecture.X86_64)
-        self.addCleanup(_p.stop)
 
         self.test_instance = _create_test_instance()
         network_info = objects.InstanceInfoCache(
@@ -2227,6 +2225,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         instance_ref.info_cache = objects.InstanceInfoCache(
             network_info=network_info)
 
+        pci_utils.get_mac_by_pci_address.side_effect = None
+        pci_utils.get_mac_by_pci_address.return_value = 'da:d1:f2:91:95:c1'
         with test.nested(
             mock.patch('nova.objects.VirtualInterfaceList'
                        '.get_by_instance_uuid', return_value=vifs),
@@ -2236,8 +2236,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                        return_value=guest),
             mock.patch.object(nova.virt.libvirt.guest.Guest, 'get_xml_desc',
                               return_value=xml),
-            mock.patch.object(pci_utils, 'get_mac_by_pci_address',
-                              return_value='da:d1:f2:91:95:c1')):
+        ):
             metadata_obj = drvr._build_device_metadata(self.context,
                                                        instance_ref)
             metadata = metadata_obj.devices
@@ -15812,9 +15811,10 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertEqual(ip, CONF.my_ip)
 
     @mock.patch.object(libvirt_driver.LOG, 'warning')
-    @mock.patch('nova.compute.utils.get_machine_ips')
-    def test_check_my_ip(self, mock_ips, mock_log):
-        mock_ips.return_value = ['8.8.8.8', '75.75.75.75']
+    def test_check_my_ip(self, mock_log):
+
+        self.libvirt.mock_get_machine_ips.return_value = [
+            '8.8.8.8', '75.75.75.75']
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
         drvr._check_my_ip()
         mock_log.assert_called_once_with(u'my_ip address (%(my_ip)s) was '
@@ -15835,6 +15835,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
         service_mock = mock.MagicMock()
         service_mock.disabled.return_value = False
+        drvr._host._init_events.return_value = None
         with test.nested(
             mock.patch.object(drvr._host, "_connect",
                               side_effect=fakelibvirt.make_libvirtError(
@@ -15842,8 +15843,6 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                   "Failed to connect to host",
                                   error_code=
                                   fakelibvirt.VIR_ERR_INTERNAL_ERROR)),
-            mock.patch.object(drvr._host, "_init_events",
-                              return_value=None),
             mock.patch.object(objects.Service, "get_by_compute_host",
                               return_value=service_mock)):
 
@@ -15858,6 +15857,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
         service_mock = mock.MagicMock()
         service_mock.disabled.return_value = False
+        drvr._host._init_events.return_value = None
         with test.nested(
             mock.patch.object(drvr._host, "_connect",
                               side_effect=fakelibvirt.make_libvirtError(
@@ -15865,8 +15865,6 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                   "Failed to connect to host",
                                   error_code=
                                   fakelibvirt.VIR_ERR_INTERNAL_ERROR)),
-            mock.patch.object(drvr._host, "_init_events",
-                              return_value=None),
             mock.patch.object(host.Host, "has_min_version",
                               return_value=True),
             mock.patch.object(drvr, "_do_quality_warnings",
@@ -15885,11 +15883,10 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
         service_mock = mock.MagicMock()
         service_mock.disabled.return_value = True
+        drvr._host._init_events.return_value = None
         with test.nested(
             mock.patch.object(drvr._host, "_connect",
                               return_value=mock.MagicMock()),
-            mock.patch.object(drvr._host, "_init_events",
-                              return_value=None),
             mock.patch.object(host.Host, "has_min_version",
                               return_value=True),
             mock.patch.object(drvr, "_do_quality_warnings",
@@ -17377,12 +17374,11 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         got = drvr._get_cpu_info()
         self.assertEqual(want, got)
 
-    @mock.patch.object(pci_utils, 'get_ifname_by_pci_address',
-                return_value='ens1')
     @mock.patch.object(host.Host, 'list_pci_devices',
                        return_value=['pci_0000_04_00_3', 'pci_0000_04_10_7',
                                      'pci_0000_04_11_7'])
-    def test_get_pci_passthrough_devices(self, mock_list, mock_get_ifname):
+    def test_get_pci_passthrough_devices(self, mock_list):
+        pci_utils.get_ifname_by_pci_address.return_value = 'ens1'
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
 
@@ -17455,7 +17451,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         # The first call for every VF is to determine parent_ifname and
         # the second call to determine the MAC address.
-        mock_get_ifname.assert_has_calls([
+        pci_utils.get_ifname_by_pci_address.assert_has_calls([
             mock.call('0000:04:10.7', pf_interface=True),
             mock.call('0000:04:11.7', pf_interface=True),
         ])
diff --git a/nova/tests/unit/virt/libvirt/test_host.py b/nova/tests/unit/virt/libvirt/test_host.py
index 7629de3aa3..42234baa3a 100644
--- a/nova/tests/unit/virt/libvirt/test_host.py
+++ b/nova/tests/unit/virt/libvirt/test_host.py
@@ -71,11 +71,10 @@ class HostTestCase(test.NoDBTestCase):
         self.useFixture(nova_fixtures.LibvirtFixture())
         self.host = host.Host("qemu:///system")
 
-    @mock.patch("nova.virt.libvirt.host.Host._init_events")
-    def test_repeat_initialization(self, mock_init_events):
+    def test_repeat_initialization(self):
         for i in range(3):
             self.host.initialize()
-        mock_init_events.assert_called_once_with()
+        self.host._init_events.assert_called_once_with()
 
     @mock.patch.object(fakelibvirt.virConnect, "registerCloseCallback")
     def test_close_callback(self, mock_close):
@@ -1113,8 +1112,9 @@ Active:          8381604 kB
         expect_vf = ["rx", "tx", "sg", "tso", "gso", "gro", "rxvlan", "txvlan"]
         self.assertEqual(expect_vf, actualvf)
 
-    @mock.patch.object(pci_utils, 'get_ifname_by_pci_address')
-    def test_get_pcidev_info_non_nic(self, mock_get_ifname):
+    def test_get_pcidev_info_non_nic(self):
+        pci_utils.get_mac_by_pci_address.side_effect = (
+            exception.PciDeviceNotFoundById('0000:04:00.3'))
         dev_name = "pci_0000_04_11_7"
         pci_dev = fakelibvirt.NodeDevice(
             self.host._get_connection(),
@@ -1128,11 +1128,10 @@ Active:          8381604 kB
             'parent_addr': '0000:04:00.3',
         }
         self.assertEqual(expect_vf, actual_vf)
-        mock_get_ifname.assert_not_called()
+        pci_utils.get_ifname_by_pci_address.assert_not_called()
 
-    @mock.patch.object(pci_utils, 'get_ifname_by_pci_address',
-                return_value='ens1')
-    def test_get_pcidev_info(self, mock_get_ifname):
+    def test_get_pcidev_info(self):
+        pci_utils.get_ifname_by_pci_address.return_value = 'ens1'
         devs = {
             "pci_0000_04_00_3", "pci_0000_04_10_7", "pci_0000_04_11_7",
             "pci_0000_04_00_1", "pci_0000_03_00_0", "pci_0000_03_00_1"
diff --git a/nova/tests/unit/virt/libvirt/test_vif.py b/nova/tests/unit/virt/libvirt/test_vif.py
index 689b13007e..88ab3565a0 100644
--- a/nova/tests/unit/virt/libvirt/test_vif.py
+++ b/nova/tests/unit/virt/libvirt/test_vif.py
@@ -517,18 +517,17 @@ class LibvirtVifTestCase(test.NoDBTestCase):
     def setUp(self):
         super(LibvirtVifTestCase, self).setUp()
 
-        self.useFixture(nova_fixtures.LibvirtFixture(stub_os_vif=False))
+        self.libvirt = self.useFixture(
+            nova_fixtures.LibvirtFixture(stub_os_vif=False))
 
         # os_vif.initialize is typically done in nova-compute startup
         os_vif.initialize()
         self.setup_os_vif_objects()
 
         # multiqueue configuration is host OS specific
-        _a = mock.patch('os.uname')
-        self.mock_uname = _a.start()
+        self.mock_uname = self.libvirt.mock_uname
         self.mock_uname.return_value = fakelibvirt.os_uname(
             'Linux', '', '5.10.13-200-generic', '', 'x86_64')
-        self.addCleanup(_a.stop)
 
     def _get_node(self, xml):
         doc = etree.fromstring(xml)
@@ -965,14 +964,9 @@ class LibvirtVifTestCase(test.NoDBTestCase):
                                   self.vif_bridge,
                                   self.vif_bridge['network']['bridge'])
 
-    @mock.patch.object(pci_utils, 'get_ifname_by_pci_address')
-    @mock.patch.object(pci_utils, 'get_vf_num_by_pci_address', return_value=1)
-    @mock.patch('nova.privsep.linux_net.set_device_macaddr')
-    @mock.patch('nova.privsep.linux_net.set_device_macaddr_and_vlan')
-    def _test_hw_veb_op(self, op, vlan, mock_set_macaddr_and_vlan,
-                        mock_set_macaddr, mock_get_vf_num,
-                        mock_get_ifname):
-        mock_get_ifname.side_effect = ['eth1', 'eth13']
+    def _test_hw_veb_op(self, op, vlan):
+        self.libvirt.mock_get_vf_num_by_pci_address.return_value = 1
+        pci_utils.get_ifname_by_pci_address.side_effect = ['eth1', 'eth13']
         vlan_id = int(vlan)
         port_state = 'up' if vlan_id > 0 else 'down'
         mac = ('00:00:00:00:00:00' if op.__name__ == 'unplug'
@@ -987,10 +981,13 @@ class LibvirtVifTestCase(test.NoDBTestCase):
             'set_macaddr': [mock.call('eth13', mac, port_state=port_state)]
         }
         op(self.instance, self.vif_hw_veb_macvtap)
-        mock_get_ifname.assert_has_calls(calls['get_ifname'])
-        mock_get_vf_num.assert_has_calls(calls['get_vf_num'])
-        mock_set_macaddr.assert_has_calls(calls['set_macaddr'])
-        mock_set_macaddr_and_vlan.assert_called_once_with(
+        pci_utils.get_ifname_by_pci_address.assert_has_calls(
+            calls['get_ifname'])
+        self.libvirt.mock_get_vf_num_by_pci_address.assert_has_calls(
+            calls['get_vf_num'])
+        self.libvirt.mock_set_device_macaddr.assert_has_calls(
+            calls['set_macaddr'])
+        self.libvirt.mock_set_device_macaddr_and_vlan.assert_called_once_with(
             'eth1', 1, mock.ANY, vlan_id)
 
     def test_plug_hw_veb(self):
@@ -1198,9 +1195,8 @@ class LibvirtVifTestCase(test.NoDBTestCase):
         self.assertEqual(1, len(node))
         self._assertPciEqual(node, self.vif_hostdev_physical)
 
-    @mock.patch.object(pci_utils, 'get_ifname_by_pci_address',
-                       return_value='eth1')
-    def test_hw_veb_driver_macvtap(self, mock_get_ifname):
+    def test_hw_veb_driver_macvtap(self):
+        pci_utils.get_ifname_by_pci_address.return_value = 'eth1'
         d = vif.LibvirtGenericVIFDriver()
         xml = self._get_instance_xml(d, self.vif_hw_veb_macvtap)
         node = self._get_node(xml)