Fix is_browser_on_page method for Studio Container page

common/test/acceptance/pages/studio/container.py

@@ -37,15 +37,19 @@ class ContainerPage(PageObject):
     def is_browser_on_page(self):
 
         def _is_finished_loading():
-            # Wait until all components have been loaded
-            is_done = len(self.q(css=XBlockWrapper.BODY_SELECTOR).results) == len(
-                self.q(css='{} .xblock'.format(XBlockWrapper.BODY_SELECTOR)).results)
+            # Wait until all components have been loaded.
+            # See common/static/coffee/src/xblock/core.coffee which adds the
+            # class "xblock-initialized" at the end of initializeBlock
+            num_wrappers = len(self.q(css=XBlockWrapper.BODY_SELECTOR).results)
+            num_xblocks_init = len(self.q(css='{} .xblock.xblock-initialized'.format(XBlockWrapper.BODY_SELECTOR)).results)
+            is_done = num_wrappers == num_xblocks_init
             return (is_done, is_done)
 
         # First make sure that an element with the view-container class is present on the page,
-        # and then wait to make sure that the xblocks are all there.
+        # and then wait for the loading spinner to go away and all the xblocks to be initialized.
         return (
             self.q(css='body.view-container').present and
+            self.q(css='div.ui-loading.is-hidden').present and
             Promise(_is_finished_loading, 'Finished rendering the xblock wrappers.').fulfill()
         )