fix move content to root case

tracim/lib/core/content.py

         item.parent = new_parent
         if new_workspace:
             item.workspace = new_workspace
-            if new_parent.workspace_id != new_workspace.workspace_id:
+            if new_parent and \
+                    new_parent.workspace_id != new_workspace.workspace_id:
                 raise NotSameWorkspace(
                     'new parent workspace and new workspace should be the same.'
                 )
         else:
-            item.workspace = new_parent.workspace
+            if new_parent:
+                item.workspace = new_parent.workspace
 
         item.revision_type = ActionDescription.MOVE
 

tracim/tests/functional/test_workspaces.py

         assert not [content for content in new_folder1_contents if content['id'] == 8]  # nopep8
         assert [content for content in new_folder2_contents if content['id'] == 8]  # nopep8
 
+    def test_api_put_move_content__ok_200__to_root(self):
+        """
+        Move content
+        move Apple_Pie (content_id: 8)
+        from Desserts folder(content_id: 3) to root (content_id: 0)
+        of workspace Recipes.
+        """
+        self.testapp.authorization = (
+            'Basic',
+            (
+                'admin@admin.admin',
+                'admin@admin.admin'
+            )
+        )
+        params = {
+            'new_parent_id': '0',  # root
+        }
+        params_folder1 = {
+            'parent_id': 3,
+            'show_archived': 0,
+            'show_deleted': 0,
+            'show_active': 1,
+        }
+        params_folder2 = {
+            'parent_id': 0,
+            'show_archived': 0,
+            'show_deleted': 0,
+            'show_active': 1,
+        }
+        folder1_contents = self.testapp.get('/api/v2/workspaces/2/contents', params=params_folder1, status=200).json_body  # nopep8
+        folder2_contents = self.testapp.get('/api/v2/workspaces/2/contents', params=params_folder2, status=200).json_body  # nopep8
+        assert [content for content in folder1_contents if content['id'] == 8]  # nopep8
+        assert not [content for content in folder2_contents if content['id'] == 8]  # nopep8
+        # TODO - G.M - 2018-06-163 - Check content
+        res = self.testapp.put_json(
+            '/api/v2/workspaces/2/contents/8/move',
+            params=params,
+            status=200
+        )
+        new_folder1_contents = self.testapp.get('/api/v2/workspaces/2/contents', params=params_folder1, status=200).json_body  # nopep8
+        new_folder2_contents = self.testapp.get('/api/v2/workspaces/2/contents', params=params_folder2, status=200).json_body  # nopep8
+        assert not [content for content in new_folder1_contents if content['id'] == 8]  # nopep8
+        assert [content for content in new_folder2_contents if content['id'] == 8]  # nopep8
+
     def test_api_put_move_content__ok_200__with_workspace_id(self):
         """
         Move content
         assert not [content for content in new_folder1_contents if content['id'] == 8]  # nopep8
         assert [content for content in new_folder2_contents if content['id'] == 8]  # nopep8
 
+    def test_api_put_move_content__ok_200__to_another_workspace_root(self):
+        """
+        Move content
+        move Apple_Pie (content_id: 8)
+        from Desserts folder(content_id: 3) to root (content_id: 0)
+        of workspace Business.
+        """
+        self.testapp.authorization = (
+            'Basic',
+            (
+                'admin@admin.admin',
+                'admin@admin.admin'
+            )
+        )
+        params = {
+            'new_parent_id': '0', # root
+            'new_workspace_id': '1',
+        }
+        params_folder1 = {
+            'parent_id': 3,
+            'show_archived': 0,
+            'show_deleted': 0,
+            'show_active': 1,
+        }
+        params_folder2 = {
+            'parent_id': 0,
+            'show_archived': 0,
+            'show_deleted': 0,
+            'show_active': 1,
+        }
+        folder1_contents = self.testapp.get('/api/v2/workspaces/2/contents', params=params_folder1, status=200).json_body  # nopep8
+        folder2_contents = self.testapp.get('/api/v2/workspaces/1/contents', params=params_folder2, status=200).json_body  # nopep8
+        assert [content for content in folder1_contents if content['id'] == 8]  # nopep8
+        assert not [content for content in folder2_contents if content['id'] == 8]  # nopep8
+        # TODO - G.M - 2018-06-163 - Check content
+        res = self.testapp.put_json(
+            '/api/v2/workspaces/2/contents/8/move',
+            params=params,
+            status=200
+        )
+        new_folder1_contents = self.testapp.get('/api/v2/workspaces/2/contents', params=params_folder1, status=200).json_body  # nopep8
+        new_folder2_contents = self.testapp.get('/api/v2/workspaces/1/contents', params=params_folder2, status=200).json_body  # nopep8
+        assert not [content for content in new_folder1_contents if content['id'] == 8]  # nopep8
+        assert [content for content in new_folder2_contents if content['id'] == 8]  # nopep8
+
     def test_api_put_move_content__err_400__wrong_workspace_id(self):
         """
         Move content