Added 'goal' ObjectField for Strategy object

In this changeset, I added the "goal" ObjectField which can
either be loaded by setting the new "eager" parameter as True or
not loaded (as before) by setting it to False.
The advantage of introducing this eager parameter is that this way,
we can reduce to a minimum the overhead of DB queries whenever the
related goal is not actually needed.

Partially-Implements: blueprint watcher-versioned-objects
Change-Id: I103c9ed161d2cedf7b43c55f9e095ef66bf44dea

watcher/tests/api/v1/test_strategies.py

@@ -21,6 +21,11 @@ from watcher.tests.objects import utils as obj_utils
 
 class TestListStrategy(api_base.FunctionalTest):
 
+    def setUp(self):
+        super(TestListStrategy, self).setUp()
+        self.fake_goal = obj_utils.create_test_goal(
+            self.context, uuid=utils.generate_uuid())
+
     def _assert_strategy_fields(self, strategy):
         strategy_fields = ['uuid', 'name', 'display_name', 'goal_uuid']
         for field in strategy_fields:
@@ -61,7 +66,6 @@ class TestListStrategy(api_base.FunctionalTest):
         self.assertEqual(404, response.status_int)
 
     def test_detail(self):
-        obj_utils.create_test_goal(self.context)
         strategy = obj_utils.create_test_strategy(self.context)
         response = self.get_json('/strategies/detail')
         self.assertEqual(strategy.uuid, response['strategies'][0]["uuid"])
@@ -78,7 +82,6 @@ class TestListStrategy(api_base.FunctionalTest):
         self.assertEqual(404, response.status_int)
 
     def test_many(self):
-        obj_utils.create_test_goal(self.context)
         strategy_list = []
         for idx in range(1, 6):
             strategy = obj_utils.create_test_strategy(
@@ -132,12 +135,12 @@ class TestListStrategy(api_base.FunctionalTest):
     def test_filter_by_goal_uuid(self):
         goal1 = obj_utils.create_test_goal(
             self.context,
-            id=1,
+            id=2,
             uuid=utils.generate_uuid(),
             name='My_Goal 1')
         goal2 = obj_utils.create_test_goal(
             self.context,
-            id=2,
+            id=3,
             uuid=utils.generate_uuid(),
             name='My Goal 2')
 
@@ -164,12 +167,12 @@ class TestListStrategy(api_base.FunctionalTest):
     def test_filter_by_goal_name(self):
         goal1 = obj_utils.create_test_goal(
             self.context,
-            id=1,
+            id=2,
             uuid=utils.generate_uuid(),
             name='My_Goal 1')
         goal2 = obj_utils.create_test_goal(
             self.context,
-            id=2,
+            id=3,
             uuid=utils.generate_uuid(),
             name='My Goal 2')
 
@@ -196,6 +199,11 @@ class TestListStrategy(api_base.FunctionalTest):
 
 class TestStrategyPolicyEnforcement(api_base.FunctionalTest):
 
+    def setUp(self):
+        super(TestStrategyPolicyEnforcement, self).setUp()
+        self.fake_goal = obj_utils.create_test_goal(
+            self.context, uuid=utils.generate_uuid())
+
     def _common_policy_check(self, rule, func, *arg, **kwarg):
         self.policy.set_rules({
             "admin_api": "(role:admin or role:administrator)",
@@ -227,8 +235,8 @@ class TestStrategyPolicyEnforcement(api_base.FunctionalTest):
             expect_errors=True)
 
 
-class TestStrategyEnforcementWithAdminContext(TestListStrategy,
-                                              api_base.AdminRoleTest):
+class TestStrategyEnforcementWithAdminContext(
+        TestListStrategy, api_base.AdminRoleTest):
 
     def setUp(self):
         super(TestStrategyEnforcementWithAdminContext, self).setUp()