Add test coverage for manage_existing API revert

New tests covers revert functionality for manage_existing API.
Tests added
1. revert ManageCastTask with volume status update check after rollback
2. revert EntryCreateTask with check DB entry is destroyed
3. revert EntryCreateTask with taskflow.Failure, no revert is expected

Partial-Bug:#1599140
Change-Id: I99df840bd7c8cd913d6045dd90871eb8894bbac8

cinder/tests/unit/volume/flows/test_manage_volume_flow.py

@@ -15,6 +15,7 @@ import inspect
 from unittest import mock
 
 import taskflow.engines
+from taskflow.types import failure as ft
 
 from cinder import context
 from cinder import exception
@@ -64,6 +65,21 @@ class ManageVolumeFlowTestCase(test.TestCase):
         create_what.pop('volume_id')
         task.execute(self.ctxt, **create_what)
 
+    def test_cast_manage_existing_revert(self):
+        volume = fake_volume.fake_volume_obj(self.ctxt)
+        volume.save = mock.MagicMock()
+
+        # Fake objects assert specs
+        task = manage_existing.ManageCastTask(
+            fake_volume_api.FakeSchedulerRpcAPI({}, self),
+            fake_volume_api.FakeDb())
+        flow_failures = [mock.MagicMock()]
+        task.revert(self.ctxt, {}, flow_failures, volume)
+
+        # Check that volume status is updated and saved
+        self.assertEqual(volume.status, 'error_managing')
+        volume.save.assert_called_once()
+
     def test_create_db_entry_task_with_multiattach(self):
 
         fake_volume_type = fake_volume.fake_volume_type_obj(
@@ -86,6 +102,32 @@ class ManageVolumeFlowTestCase(test.TestCase):
         result = task.execute(self.ctxt, **spec)
         self.assertTrue(result['volume_properties']['multiattach'])
 
+    def test_revert_manage_existing(self):
+        fake_db = fake_volume_api.FakeDb()
+        fake_db.volume_destroy = mock.MagicMock()
+
+        self.ctxt.elevated = mock.Mock()
+
+        task = manage_existing.EntryCreateTask(fake_db)
+        task.revert(self.ctxt, {'volume_id': fakes.VOLUME_ID})
+
+        # Check DB entry task is destroyed
+        fake_db.volume_destroy.assert_called_once_with(
+            self.ctxt.elevated.return_value,
+            fakes.VOLUME_ID
+        )
+
+    def test_revert_manage_existing_with_ft_failure(self):
+        fake_db = fake_volume_api.FakeDb()
+        fake_db.volume_destroy = mock.MagicMock()
+
+        mock_failure = mock.Mock(spec=ft.Failure)
+        task = manage_existing.EntryCreateTask(fake_db)
+        task.revert(self.ctxt, mock_failure)
+
+        # Check DB entry task is not destroyed
+        fake_db.volume_destroy.assert_not_called()
+
     @staticmethod
     def _stub_volume_object_get(self):
         volume = {