Wait for MathJax to render.

common/test/acceptance/tests/lms/test_lms_problems.py

@@ -275,19 +275,28 @@ class ProblemWithMathjax(ProblemsTest):
         problem_page = ProblemPage(self.browser)
         self.assertEqual(problem_page.problem_name, "MATHJAX TEST PROBLEM")
 
-        # Verify Mathjax have been rendered
-        self.assertTrue(problem_page.mathjax_rendered_in_problem, "MathJax did not rendered in body")
+        # Verify MathJax has been rendered
+        problem_page.wait_for(
+            lambda: problem_page.mathjax_rendered_in_problem,
+            description="MathJax rendered in body"
+        )
 
         # The hint button rotates through multiple hints
         problem_page.click_hint()
         self.assertIn("Hint (1 of 2): mathjax should work1", problem_page.hint_text)
-        self.assertTrue(problem_page.mathjax_rendered_in_hint, "MathJax did not rendered in problem hint")
+        problem_page.wait_for(
+            lambda: problem_page.mathjax_rendered_in_hint,
+            description="MathJax rendered in hint"
+        )
 
         # Rotate the hint and check the problem hint
         problem_page.click_hint()
 
         self.assertIn("Hint (2 of 2): mathjax should work2", problem_page.hint_text)
-        self.assertTrue(problem_page.mathjax_rendered_in_hint, "MathJax did not rendered in problem hint")
+        problem_page.wait_for(
+            lambda: problem_page.mathjax_rendered_in_hint,
+            description="MathJax rendered in hint"
+        )
 
 
 class ProblemPartialCredit(ProblemsTest):