Add objectify decorator for readability

Because it isn't inherently clear what register_if(False) does on top of
a class, a functionally equivalent objectify decorator is added to make
things a little more readable.

The register_if() decorator was also cleaned up a little bit to reuse
the register() decorator. Unit tests were also added for the register()
functions to ensure none of the functionality is changing.

Change-Id: I0bec8e7e587b81dc0484a7b39f0cf57308d3b3d4

oslo_versionedobjects/base.py

@@ -143,13 +143,16 @@ class VersionedObjectRegistry(object):
     def register_if(cls, condition):
         def wraps(obj_cls):
             if condition:
-                registry = cls()
-                registry._register_class(obj_cls)
+                obj_cls = cls.register(obj_cls)
             else:
                 _make_class_properties(obj_cls)
             return obj_cls
         return wraps
 
+    @classmethod
+    def objectify(cls, obj_cls):
+        return cls.register_if(False)(obj_cls)
+
     @classmethod
     def obj_classes(cls):
         registry = cls()

oslo_versionedobjects/tests/test_objects.py

@@ -324,6 +324,47 @@ class TestRegistry(test.TestCase):
         self.assertEqual(AVersionedObject1.reg_to, "one")
         self.assertEqual(AVersionedObject2.reg_to, "two")
 
+    @mock.patch.object(base.VersionedObjectRegistry, '__new__')
+    def test_register(self, mock_registry):
+        mock_reg_obj = mock.Mock()
+        mock_registry.return_value = mock_reg_obj
+        mock_reg_obj._register_class = mock.Mock()
+
+        class my_class(object):
+            pass
+
+        base.VersionedObjectRegistry.register(my_class)
+        mock_reg_obj._register_class.assert_called_once_with(my_class)
+
+    @mock.patch.object(base.VersionedObjectRegistry, 'register')
+    def test_register_if(self, mock_register):
+        class my_class(object):
+            pass
+
+        base.VersionedObjectRegistry.register_if(True)(my_class)
+        mock_register.assert_called_once_with(my_class)
+
+    @mock.patch.object(base, '_make_class_properties')
+    def test_register_if_false(self, mock_make_props):
+        class my_class(object):
+            pass
+
+        base.VersionedObjectRegistry.register_if(False)(my_class)
+        mock_make_props.assert_called_once_with(my_class)
+
+    @mock.patch.object(base.VersionedObjectRegistry, 'register_if')
+    def test_objectify(self, mock_register_if):
+        mock_reg_callable = mock.Mock()
+        mock_register_if.return_value = mock_reg_callable
+
+        class my_class(object):
+            pass
+
+        base.VersionedObjectRegistry.objectify(my_class)
+
+        mock_register_if.assert_called_once_with(False)
+        mock_reg_callable.assert_called_once_with(my_class)
+
 
 class TestObjMakeList(test.TestCase):