Remove write_to_file.

It only really existed to make unit testing easier back in the day,
and is trivial to move to its two callers.

Change-Id: I06c4408995d4bad0a4560e8e9cd5298d4bb6b043

nova/tests/unit/virt/libvirt/test_driver.py

@@ -14363,19 +14363,21 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         disk_info_path = os.path.join(instance_path, 'disk.info')
 
         with test.nested(
+            mock.patch('builtins.open', new_callable=mock.mock_open),
             mock.patch.object(os, 'mkdir'),
-            mock.patch('nova.virt.libvirt.utils.write_to_file'),
             mock.patch.object(drvr, '_create_images_and_backing')
         ) as (
-            mkdir, write_to_file, create_images_and_backing
+            mock_open, mkdir, create_images_and_backing
         ):
             drvr.pre_live_migration(self.context, instance,
                                     block_device_info=None,
                                     network_info=[],
                                     disk_info=jsonutils.dumps(disk_info),
                                     migrate_data=migrate_data)
-            write_to_file.assert_called_with(disk_info_path,
+
-                                             jsonutils.dumps(image_disk_info))
+            self.assertIn(mock.call(disk_info_path, 'w'), mock_open.mock_calls)
+            mock_open.return_value.write.assert_called_with(
+                jsonutils.dumps(image_disk_info))
 
     @mock.patch('nova.virt.libvirt.utils.file_open',
                 side_effect=[io.BytesIO(b''), io.BytesIO(b'')])
@@ -16292,16 +16294,16 @@ class LibvirtConnTestCase(test.NoDBTestCase,
     @mock.patch('nova.virt.libvirt.LibvirtDriver._create_images_and_backing')
     @mock.patch('nova.virt.libvirt.LibvirtDriver.'
                 '_get_instance_disk_info_from_config')
-    @mock.patch('nova.virt.libvirt.utils.write_to_file')
     @mock.patch('nova.virt.libvirt.utils.get_instance_path')
     @mock.patch('nova.virt.libvirt.LibvirtDriver._get_guest_config')
     @mock.patch('nova.virt.libvirt.blockinfo.get_disk_info')
     @mock.patch('nova.virt.libvirt.LibvirtDriver._destroy')
     @mock.patch('nova.virt.libvirt.LibvirtDriver.'
                 '_get_all_assigned_mediated_devices')
+    @mock.patch('builtins.open', new=mock.mock_open())
     def test_hard_reboot_does_not_call_glance_show(self,
             mock_get_mdev, mock_destroy, mock_get_disk_info,
-            mock_get_guest_config, mock_get_instance_path, mock_write_to_file,
+            mock_get_guest_config, mock_get_instance_path,
             mock_get_instance_disk_info, mock_create_images_and_backing,
             mock_create_domand_and_network, mock_prepare_pci_devices_for_use,
             mock_get_instance_pci_devs, mock_looping_call, mock_ensure_tree):
@@ -22375,18 +22377,17 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
     @mock.patch.object(libvirt_driver.LibvirtDriver,
                        '_create_guest_with_network')
     @mock.patch.object(libvirt_driver.LibvirtDriver, '_disk_raw_to_qcow2')
-    # Don't write libvirt xml to disk
-    @mock.patch.object(libvirt_utils, 'write_to_file')
     # NOTE(mdbooth): The following 4 mocks are required to execute
     #                get_guest_xml().
     @mock.patch.object(libvirt_driver.LibvirtDriver, '_set_host_enabled')
     @mock.patch.object(libvirt_driver.LibvirtDriver, '_build_device_metadata')
     @mock.patch('nova.privsep.utils.supports_direct_io')
     @mock.patch('nova.api.metadata.base.InstanceMetadata')
+    @mock.patch('builtins.open', new=mock.mock_open())
     def _test_finish_migration(self, mock_instance_metadata,
                                mock_supports_direct_io,
                                mock_build_device_metadata,
-                               mock_set_host_enabled, mock_write_to_file,
+                               mock_set_host_enabled,
                                mock_raw_to_qcow2,
                                mock_create_guest_with_network,
                                mock_get_info, mock_inject_data,
@@ -23761,18 +23762,19 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
     @mock.patch('nova.objects.image_meta.ImageMeta.from_image_ref')
     @mock.patch('nova.virt.libvirt.LibvirtDriver.'
                 '_get_all_assigned_mediated_devices')
-    @mock.patch('nova.virt.libvirt.utils.write_to_file')
     # NOTE(mdbooth): The following 4 mocks are required to execute
     #                get_guest_xml().
     @mock.patch.object(libvirt_driver.LibvirtDriver, '_set_host_enabled')
     @mock.patch.object(libvirt_driver.LibvirtDriver, '_build_device_metadata')
     @mock.patch('nova.privsep.utils.supports_direct_io')
     @mock.patch('nova.api.metadata.base.InstanceMetadata')
-    def _test_rescue(self, instance, mock_instance_metadata,
+    @mock.patch('builtins.open', new=mock.mock_open())
-            mock_supports_direct_io, mock_build_device_metadata,
+    def _test_rescue(
-            mock_set_host_enabled, mock_write_to_file, mock_get_mdev,
+        self, instance, mock_instance_metadata, mock_supports_direct_io,
-            mock_get_image_meta_by_ref, image_meta_dict=None, exists=None,
+        mock_build_device_metadata, mock_set_host_enabled, mock_get_mdev,
-            instance_image_meta_dict=None, block_device_info=None):
+        mock_get_image_meta_by_ref, image_meta_dict=None, exists=None,
+        instance_image_meta_dict=None, block_device_info=None,
+    ):
 
         self.flags(instances_path=self.useFixture(fixtures.TempDir()).path)
         mock_build_device_metadata.return_value = None
@@ -23929,9 +23931,8 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
         self.assertEqual(expected_kernel_ramdisk_paths,
                          kernel_ramdisk_paths)
 
-    @mock.patch('nova.virt.libvirt.utils.write_to_file')
+    @mock.patch('builtins.open', new=mock.mock_open())
-    def test_rescue_stable_device_unsupported_virt_types(self,
+    def test_rescue_stable_device_unsupported_virt_types(self):
-        mock_libvirt_write_to_file):
         network_info = _fake_network_info(self, 1)
         instance = self._create_instance({'config_drive': str(True)})
         rescue_image_meta_dict = {'id': uuids.rescue_image_id,
@@ -24087,15 +24088,16 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
             mock.patch.object(drvr, '_get_guest_xml'),
             mock.patch.object(drvr, '_create_image'),
             mock.patch.object(drvr, '_get_existing_domain_xml'),
-            mock.patch.object(libvirt_utils, 'write_to_file'),
             mock.patch.object(libvirt_utils, 'get_instance_path'),
             mock.patch('nova.virt.libvirt.blockinfo.get_disk_info'),
             mock.patch('nova.image.glance.API.get'),
-            mock.patch('nova.objects.image_meta.ImageMeta.from_dict')
+            mock.patch('nova.objects.image_meta.ImageMeta.from_dict'),
-        ) as (mock_create, mock_destroy, mock_get_guest_xml, mock_create_image,
+            mock.patch('builtins.open', new_callable=mock.mock_open),
-              mock_get_existing_xml, mock_write, mock_inst_path,
+        ) as (
-              mock_get_disk_info, mock_image_get, mock_from_dict):
+            mock_create, mock_destroy, mock_get_guest_xml, mock_create_image,
-
+            mock_get_existing_xml, mock_inst_path, mock_get_disk_info,
+            mock_image_get, mock_from_dict, mock_open,
+        ):
             self.flags(virt_type='kvm', group='libvirt')
             mock_image_get.return_value = mock.sentinel.bdm_image_meta_dict
             mock_from_dict.return_value = mock.sentinel.bdm_image_meta
@@ -24185,8 +24187,11 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
     @mock.patch.object(libvirt_utils, 'get_instance_path')
     @mock.patch.object(libvirt_utils, 'load_file')
     @mock.patch.object(host.Host, '_get_domain')
-    def _test_unrescue(self, instance, mock_get_domain, mock_load_file,
+    @mock.patch('builtins.open', new=mock.mock_open())
-                                           mock_get_instance_path):
+    def _test_unrescue(
+        self, instance, mock_get_domain, mock_load_file,
+        mock_get_instance_path,
+    ):
         dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
                     "<devices>"
                     "<disk type='block' device='disk'>"
@@ -24210,7 +24215,6 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
         with test.nested(
-                mock.patch.object(libvirt_utils, 'write_to_file'),
                 mock.patch.object(drvr, '_destroy'),
                 mock.patch.object(drvr, '_create_guest'),
                 mock.patch.object(os, 'unlink'),
@@ -24222,7 +24226,7 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
                 mock.patch.object(lvm, 'remove_volumes'),
                 mock.patch.object(glob, 'iglob',
                                   return_value=[rescue_file, rescue_dir])
-                ) as (mock_write, mock_destroy, mock_create, mock_del,
+                ) as (mock_destroy, mock_create, mock_del,
                       mock_rmtree, mock_isdir, mock_lvm_disks,
                       mock_remove_volumes, mock_glob):
             drvr.unrescue(self.context, instance)

nova/tests/unit/virt/libvirt/test_utils.py

@@ -248,17 +248,6 @@ class LibvirtUtilsTestCase(test.NoDBTestCase):
         finally:
             os.unlink(dst_path)
 
-    def test_write_to_file(self):
-        dst_fd, dst_path = tempfile.mkstemp()
-        try:
-            os.close(dst_fd)
-
-            libvirt_utils.write_to_file(dst_path, 'hello')
-            with open(dst_path, 'r') as fp:
-                self.assertEqual(fp.read(), 'hello')
-        finally:
-            os.unlink(dst_path)
-
     @mock.patch.object(compute_utils, 'disk_ops_semaphore')
     @mock.patch('nova.privsep.utils.supports_direct_io', return_value=False)
     @mock.patch('oslo_concurrency.processutils.execute')
@@ -330,8 +319,8 @@ class LibvirtUtilsTestCase(test.NoDBTestCase):
         try:
             os.close(dst_fd)
 
-            # We have a test for write_to_file. If that is sound, this suffices
+            with open(dst_path, 'w') as f:
-            libvirt_utils.write_to_file(dst_path, 'hello')
+                f.write('hello')
             self.assertEqual(libvirt_utils.load_file(dst_path), 'hello')
         finally:
             os.unlink(dst_path)
@@ -341,8 +330,8 @@ class LibvirtUtilsTestCase(test.NoDBTestCase):
         try:
             os.close(dst_fd)
 
-            # We have a test for write_to_file. If that is sound, this suffices
+            with open(dst_path, 'w') as f:
-            libvirt_utils.write_to_file(dst_path, 'hello')
+                f.write('hello')
             with libvirt_utils.file_open(dst_path, 'r') as fp:
                 self.assertEqual(fp.read(), 'hello')
         finally:

nova/virt/libvirt/driver.py

@@ -3590,7 +3590,8 @@ class LibvirtDriver(driver.ComputeDriver):
         instance_dir = libvirt_utils.get_instance_path(instance)
         unrescue_xml = self._get_existing_domain_xml(instance, network_info)
         unrescue_xml_path = os.path.join(instance_dir, 'unrescue.xml')
-        libvirt_utils.write_to_file(unrescue_xml_path, unrescue_xml)
+        with open(unrescue_xml_path, 'w') as f:
+            f.write(unrescue_xml)
 
         rescue_image_id = None
         rescue_image_meta = None
@@ -9707,8 +9708,8 @@ class LibvirtDriver(driver.ComputeDriver):
 
                 image_disk_info_path = os.path.join(instance_dir,
                                                     'disk.info')
-                libvirt_utils.write_to_file(image_disk_info_path,
+                with open(image_disk_info_path, 'w') as f:
-                                            jsonutils.dumps(image_disk_info))
+                    f.write(jsonutils.dumps(image_disk_info))
 
             if not is_shared_block_storage:
                 # Ensure images and backing files are present.

nova/virt/libvirt/utils.py

@@ -306,17 +306,6 @@ def copy_image(
             compression=compression)
 
 
-# TODO(stephenfin): This is dumb; remove it.
-def write_to_file(path: str, contents: str) -> None:
-    """Write the given contents to a file
-
-    :param path: Destination file
-    :param contents: Desired contents of the file
-    """
-    with open(path, 'w') as f:
-        f.write(contents)
-
-
 def chown_for_id_maps(
     path: str, id_maps: ty.List[vconfig.LibvirtConfigGuestIDMap],
 ) -> None: