diff --git a/common/lib/capa/capa/tests/test_html_render.py b/common/lib/capa/capa/tests/test_html_render.py
index 9bc326d..8e343ee 100644
--- a/common/lib/capa/capa/tests/test_html_render.py
+++ b/common/lib/capa/capa/tests/test_html_render.py
@@ -226,6 +226,26 @@ class CapaHtmlRenderTest(unittest.TestCase):
span_element = rendered_html.find('span')
self.assertEqual(span_element.get('attr'), "TEST")
+ def test_xml_comments_and_other_odd_things(self):
+ # Comments and processing instructions should be skipped.
+ xml_str = textwrap.dedent("""\
+ <?xml version="1.0" encoding="utf-8"?>
+ <!DOCTYPE html [
+ <!ENTITY % wacky "lxml.etree is wacky!">
+ ]>
+ <problem>
+ <!-- A commment. -->
+ <?ignore this processing instruction. ?>
+ </problem>
+ """)
+
+ # Create the problem
+ problem = new_loncapa_problem(xml_str)
+
+ # Render the HTML
+ the_html = problem.get_html()
+ self.assertRegexpMatches(the_html, r"<div>\s+</div>")
+
def _create_test_file(self, path, content_str):
test_fp = self.system.filestore.open(path, "w")
test_fp.write(content_str)