Cancel Action Plan

This patch adds feature to cancel action plan in watcher.
A General flow from watcher-api to watcher-applier is implemented.

action plan cancel can cancel any [ongoing, pending, recommended]
action plan, it will update the action states also to "cancelled".
For ongoing actions in action plan, actions needs to be aborted.
Seperate patches will be added to support abort operation
in each action.

Notification part is addressed by a seperate blueprint.
https://blueprints.launchpad.net/watcher/+spec/notifications-actionplan-cancel

Change-Id: I895a5eaca5239d5657702c8d1875b9ece21682dc
Partially-Implements: blueprint cancel-action-plan

watcher/tests/applier/action_plan/test_default_action_handler.py

@@ -19,6 +19,7 @@ import mock
 
 from watcher.applier.action_plan import default
 from watcher.applier import default as ap_applier
+from watcher.common import exception
 from watcher import notifications
 from watcher import objects
 from watcher.objects import action_plan as ap_objects
@@ -99,3 +100,27 @@ class TestDefaultActionPlanHandler(base.DbTestCase):
             self.m_action_plan_notifications
                 .send_action_notification
                 .call_args_list)
+
+    @mock.patch.object(objects.ActionPlan, "get_by_uuid")
+    def test_cancel_action_plan(self, m_get_action_plan):
+        m_get_action_plan.return_value = self.action_plan
+        self.action_plan.state = ap_objects.State.CANCELLED
+        self.action_plan.save()
+        command = default.DefaultActionPlanHandler(
+            self.context, mock.MagicMock(), self.action_plan.uuid)
+        command.execute()
+        action = self.action.get_by_uuid(self.context, self.action.uuid)
+        self.assertEqual(ap_objects.State.CANCELLED, self.action_plan.state)
+        self.assertEqual(objects.action.State.CANCELLED, action.state)
+
+    @mock.patch.object(ap_applier.DefaultApplier, "execute")
+    @mock.patch.object(objects.ActionPlan, "get_by_uuid")
+    def test_cancel_action_plan_with_exception(self, m_get_action_plan,
+                                               m_execute):
+        m_get_action_plan.return_value = self.action_plan
+        m_execute.side_effect = exception.ActionPlanCancelled(
+            self.action_plan.uuid)
+        command = default.DefaultActionPlanHandler(
+            self.context, mock.MagicMock(), self.action_plan.uuid)
+        command.execute()
+        self.assertEqual(ap_objects.State.CANCELLED, self.action_plan.state)