fix bug and add unit test

cms/djangoapps/contentstore/tests/test_contentstore.py

@@ -348,6 +348,43 @@ class ContentStoreToyCourseTest(ModuleStoreTestCase):
 
         self.assertEqual(course.tabs, expected_tabs)
 
+    def test_create_static_tab_and_rename(self):
+        module_store = modulestore('direct')
+        CourseFactory.create(org='edX', course='999', display_name='Robot Super Course')
+        course_location = Location(['i4x', 'edX', '999', 'course', 'Robot_Super_Course', None])    
+
+        item = ItemFactory.create(parent_location=course_location, category='static_tab', display_name="My Tab")
+
+        course = module_store.get_item(course_location)
+
+        expected_tabs = []
+        expected_tabs.append({u'type': u'courseware'})
+        expected_tabs.append({u'type': u'course_info', u'name': u'Course Info'})
+        expected_tabs.append({u'type': u'textbooks'})
+        expected_tabs.append({u'type': u'discussion', u'name': u'Discussion'})
+        expected_tabs.append({u'type': u'wiki', u'name': u'Wiki'})
+        expected_tabs.append({u'type': u'progress', u'name': u'Progress'})
+        expected_tabs.append({u'type': u'static_tab', u'name': u'My Tab', u'url_slug': u'My_Tab'})
+
+        self.assertEqual(course.tabs, expected_tabs)
+
+        item.display_name = 'Updated'
+        item.save()
+        module_store.update_metadata(item.location, own_metadata(item))
+
+        course = module_store.get_item(course_location)
+
+        expected_tabs = []
+        expected_tabs.append({u'type': u'courseware'})
+        expected_tabs.append({u'type': u'course_info', u'name': u'Course Info'})
+        expected_tabs.append({u'type': u'textbooks'})
+        expected_tabs.append({u'type': u'discussion', u'name': u'Discussion'})
+        expected_tabs.append({u'type': u'wiki', u'name': u'Wiki'})
+        expected_tabs.append({u'type': u'progress', u'name': u'Progress'})
+        expected_tabs.append({u'type': u'static_tab', u'name': u'Updated', u'url_slug': u'My_Tab'})
+
+        self.assertEqual(course.tabs, expected_tabs)
+
     def test_static_tab_reordering(self):
         module_store = modulestore('direct')
         CourseFactory.create(org='edX', course='999', display_name='Robot Super Course')

common/lib/xmodule/xmodule/modulestore/mongo/base.py

@@ -794,7 +794,7 @@ class MongoModuleStore(ModuleStoreBase):
             existing_tabs = course.tabs or []
             for tab in existing_tabs:
                 if tab.get('url_slug') == loc.name:
-                    tab['name'] = tab.get('name', metadata.get('display_name'))
+                    tab['name'] = metadata.get('display_name', tab.get('name'))
                     break
             course.tabs = existing_tabs
             # Save the updates to the course to the MongoKeyValueStore