Fix a bug in extracting HTML

Update tests to reflect new behavior.

common/lib/capa/capa/capa_problem.py

@@ -331,7 +331,7 @@ class LoncapaProblem(object):
         '''
         Main method called externally to get the HTML to be rendered for this capa Problem.
         '''
-        html = contextualize_text(etree.tostring(self.extracted_tree), self.context)
+        html = contextualize_text(etree.tostring(self._extract_html(self.tree)), self.context)
         return html
 
 

common/lib/capa/capa/tests/test_html_render.py

@@ -125,6 +125,8 @@ class CapaHtmlRenderTest(unittest.TestCase):
         expected_solution_context = {'id': '1_solution_1'}
 
         expected_calls = [mock.call('textline.html', expected_textline_context),
+                mock.call('solutionspan.html', expected_solution_context),
+                mock.call('textline.html', expected_textline_context),
                 mock.call('solutionspan.html', expected_solution_context)]
 
         self.assertEqual(test_system.render_template.call_args_list,