Ensure cohort management section has loaded.

TNL-2120, TE-849

The parent .cohort-management class was loading faster than its children (which makes sense). However,
flakiness existed on these tests because browser actions were depending on child elements that had not
painted yet.

Tested this using chrome with no X11 forwarding for extra speed. That exposed the ajax call
as well as the sub-class rendering issues.

common/test/acceptance/pages/lms/instructor_dashboard.py

@@ -34,6 +34,8 @@ class InstructorDashboardPage(CoursePage):
         """
         self.q(css='a[data-section=cohort_management]').first.click()
         cohort_management_section = CohortManagementSection(self.browser)
+        # The first time cohort management is selected, an ajax call is made.
+        cohort_management_section.wait_for_ajax()
         cohort_management_section.wait_for_page()
         return cohort_management_section
 
@@ -111,7 +113,21 @@ class CohortManagementSection(PageObject):
     }
 
     def is_browser_on_page(self):
-        return self.q(css='.cohort-management').present
+        """
+        Cohorts management exists under one class; however, render time can be longer because of sub-classes
+        that must be rendered beneath it. To determine if the browser is on the cohorts management page (and
+        allow for it to fully-render), we need to consider three different states of the page:
+        * When no cohorts have been added yet
+        * When a new cohort is being added (a confirmation state)
+        * When cohorts exist (the traditional management page)
+        """
+        cohorts_warning_title = '.message-warning .message-title'
+
+        if self.q(css=cohorts_warning_title).visible:
+            return self.q(css='.message-title').text[0] == u'You currently have no cohorts configured'
+        # The page may be in either the traditional management state, or an 'add new cohort' state.
+        # Confirm the CSS class is visible because the CSS class can exist on the page even in different states.
+        return self.q(css='.cohort-management-nav').visible or self.q(css='.new-cohort-form').visible
 
     def _bounded_selector(self, selector):
         """
@@ -480,13 +496,8 @@ class CohortManagementSection(PageObject):
         """
         Shows the discussion topics.
         """
-        EmptyPromise(
-            lambda: self.q(css=self._bounded_selector('.toggle-cohort-management-discussions')).results != 0,
-            "Waiting for discussion section to show"
-        ).fulfill()
-
-        # If the discussion topic section has not yet been toggled on, click on the toggle link.
-        self.q(css=self._bounded_selector(".toggle-cohort-management-discussions")).click()
+        self.q(css=self._bounded_selector(".toggle-cohort-management-discussions")).first.click()
+        self.wait_for_element_visibility("#cohort-management-discussion-topics", "Waiting for discussions to appear")
 
     def discussion_topics_visible(self):
         """

common/test/acceptance/tests/discussion/test_cohort_management.py

@@ -4,7 +4,6 @@ End-to-end tests related to the cohort management on the LMS Instructor Dashboar
 """
 
 from datetime import datetime
-from flaky import flaky
 
 from pytz import UTC, utc
 from bok_choy.promise import EmptyPromise
@@ -719,7 +718,6 @@ class CohortDiscussionTopicsTest(UniqueCourseTest, CohortTestMixin):
         self.reload_page()
         self.assertEqual(self.cohort_management_page.get_cohorted_topics_count(key), cohorted_topics)
 
-    @flaky  # TODO: fix this, see TNL-2120
     def test_cohort_course_wide_discussion_topic(self):
         """
         Scenario: cohort a course-wide discussion topic.