diff -r 66243fb5e3fc -r 2ff785d7026c server/python/django2/renkanmanager/tests/v1_0/tests_workspace.py
--- a/server/python/django2/renkanmanager/tests/v1_0/tests_workspace.py	Tue Mar 01 17:39:39 2016 +0100
+++ b/server/python/django2/renkanmanager/tests/v1_0/tests_workspace.py	Thu Mar 03 17:09:27 2016 +0100
@@ -11,10 +11,10 @@
     
     def setUp(self):
         User.objects.create_superuser("blop", "blop@blop.com", "blop")
-        self.user = User.objects.get(username="blop")
+        self.user = User.objects.get_by_natural_key("blop")
         _ = self.client.login(username="blop", password="blop")
         User.objects.create_user("blip", "blip@blip.com", "blip")
-        self.unauthorized_user = User.objects.get(username="blip")
+        self.unauthorized_user = User.objects.get_by_natural_key("blip")
     
     def test_post_workspace(self):
         
@@ -31,12 +31,12 @@
         
         # Checking data
         #    in the response
-        self.assertEqual(post_response_dict.get("workspace_created_by"), self.user.username)
+        self.assertEqual(post_response_dict.get("workspace_created_by"), getattr(self.user, User.USERNAME_FIELD))
         self.assertEqual(post_response_dict.get("title"), test_title)
         #    in the database
         created_workspace_guid = post_response_dict.get("id")
         created_workspace = Workspace.objects.get(workspace_guid=created_workspace_guid)
-        self.assertEqual(created_workspace.creator.username, self.user.username)
+        self.assertEqual(getattr(created_workspace.creator, User.USERNAME_FIELD), getattr(self.user, User.USERNAME_FIELD))
         self.assertEqual(created_workspace.title, test_title)
         
         # Checking permission
@@ -117,7 +117,7 @@
         get_response_dict = json.loads(get_response.content.decode())
         self.assertEqual(test_workspace_guid, get_response_dict.get("id", ""))
         self.assertEqual(test_title, get_response_dict.get("title", ""))
-        self.assertEqual(self.user.username, get_response_dict.get("workspace_created_by", ""))
+        self.assertEqual(getattr(self.user, User.USERNAME_FIELD), get_response_dict.get("workspace_created_by", ""))
         self.assertEqual(2, get_response_dict.get("renkan_count"))
         
         ###################################################
@@ -163,13 +163,13 @@
         
         # Checking data
         #    in the response
-        self.assertEqual(put_response_dict.get("workspace_created_by"), self.user.username)
+        self.assertEqual(put_response_dict.get("workspace_created_by"), getattr(self.user, User.USERNAME_FIELD))
         self.assertEqual(put_response_dict.get("title"), edited_title)
         self.assertEqual(put_response_dict.get("renkan_count"), 0)
         #    in the database
         edited_workspace_guid = put_response_dict.get("id")
         edited_workspace = Workspace.objects.get(workspace_guid=edited_workspace_guid)
-        self.assertEqual(edited_workspace.creator.username, self.user.username)
+        self.assertEqual(getattr(edited_workspace.creator, User.USERNAME_FIELD), getattr(self.user, User.USERNAME_FIELD))
         self.assertEqual(edited_workspace.title, edited_title)
         self.assertEqual(edited_workspace.renkan_count, 0)