Improving Image _json_to_obj method

The previous method had a side-effect of actually deleting the entry
from object passed and therefore could not be used in a static context,
e.g. in a @classmethod

Change-Id: I0e560452f902db6c6b3bda73bc21b95c9b706cd6

cloudcafe/images/v1/models/image.py

@@ -13,6 +13,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 """
+from copy import deepcopy
 
 from cafe.engine.models.base import AutoMarshallingModel
 from cloudcafe.compute.common.equality_tools import EqualityTools
@@ -98,8 +99,8 @@ class Image(AutoMarshallingModel):
     @classmethod
     def _dict_to_obj(cls, json_dict):
         """@summary: Processing dates in converting string to date objects"""
-        json_dict['id_'] = json_dict['id']
-        del json_dict['id']
+        json_dict = deepcopy(json_dict)
+        json_dict['id_'] = json_dict.pop('id')
 
         for date_key in ['created_at', 'updated_at', 'deleted_at']:
             if json_dict.get(date_key):

metatests/images/v1_0/models/image_test.py

@@ -67,7 +67,7 @@ class TestImage(object):
         assert member1 in self.image_one.members_list
 
     def test_remove_member_from_an_image(self):
-        image = Image._json_to_obj(self.raw_image_str)
+        image = Image._dict_to_obj(self._dict)
         member1 = Member(member_id='1')
         member2 = Member(member_id='2')