From 87d135a40cfdc653bb58f24eb0a427a3c9294923 Mon Sep 17 00:00:00 2001
From: Usman Khalid <2200617@gmail.com>
Date: Fri, 19 Sep 2014 15:57:00 +0500
Subject: [PATCH 1/2] Added tests for unparsable matlab grader response.

TNL-388
---
 common/lib/capa/capa/tests/test_inputtypes.py | 29 +++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/common/lib/capa/capa/tests/test_inputtypes.py b/common/lib/capa/capa/tests/test_inputtypes.py
index 1982a5f926..8d02edd4e8 100644
--- a/common/lib/capa/capa/tests/test_inputtypes.py
+++ b/common/lib/capa/capa/tests/test_inputtypes.py
@@ -26,6 +26,7 @@ import xml.sax.saxutils as saxutils
 
 from . import test_capa_system
 from capa import inputtypes
+from capa.checker import DemoSystem
 from mock import ANY, patch
 from pyparsing import ParseException
 
@@ -727,6 +728,34 @@ class MatlabTest(unittest.TestCase):
         received = fromstring(context['queue_msg'])
         html_tree_equal(received, expected)
 
+    def test_rendering_with_invalid_queue_msg(self):
+        self.the_input.queue_msg = (u"<div class='matlabResponse'><div style='white-space:pre' class='commandWindowOutput'>"
+                                    u"\nans =\n\n\u0002\n\n</div><ul></ul></div>")
+        context = self.the_input._get_render_context()  # pylint: disable=protected-access
+
+        self.maxDiff = None
+        expected = {
+            'STATIC_URL': '/dummy-static/',
+            'id': 'prob_1_2',
+            'value': 'print "good evening"',
+            'status': inputtypes.Status('queued'),
+            'msg': self.the_input.submitted_msg,
+            'mode': self.mode,
+            'rows': self.rows,
+            'cols': self.cols,
+            'queue_msg': "<span>Error running code.</span>",
+            'linenumbers': 'true',
+            'hidden': '',
+            'tabsize': int(self.tabsize),
+            'button_enabled': True,
+            'queue_len': '3',
+            'matlab_editor_js': '/dummy-static/js/vendor/CodeMirror/octave.js',
+        }
+
+        self.assertEqual(context, expected)
+        self.the_input.capa_system.render_template = DemoSystem().render_template
+        self.the_input.get_html()  # Should not raise an exception
+
     def test_matlab_queue_message_allowed_tags(self):
         """
         Test allowed tags.

From ea032c58ca5b35f149542b146d02b91c92fb687e Mon Sep 17 00:00:00 2001
From: Usman Khalid <2200617@gmail.com>
Date: Fri, 19 Sep 2014 15:58:29 +0500
Subject: [PATCH 2/2] If matlab grader sent unparsable response, show error
 message instead of trying to render the response.

TNL-388
---
 common/lib/capa/capa/inputtypes.py | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/common/lib/capa/capa/inputtypes.py b/common/lib/capa/capa/inputtypes.py
index 0185b5fd7d..2f30f634dd 100644
--- a/common/lib/capa/capa/inputtypes.py
+++ b/common/lib/capa/capa/inputtypes.py
@@ -808,6 +808,7 @@ class MatlabInput(CodeInput):
         Handle matlab-specific parsing
         """
         _ = self.capa_system.i18n.ugettext
+
         submitted_msg = _("Submitted. As soon as a response is returned, "
                           "this message will be replaced by that feedback.")
         self.submitted_msg = submitted_msg
@@ -889,9 +890,23 @@ class MatlabInput(CodeInput):
 
     def _extra_context(self):
         """ Set up additional context variables"""
+
+        _ = self.capa_system.i18n.ugettext
+
+        queue_msg = self.queue_msg
+        if len(self.queue_msg) > 0:  # An empty string cannot be parsed as XML but is okay to include in the template.
+            try:
+                etree.XML(u'<div>{0}</div>'.format(self.queue_msg))
+            except etree.XMLSyntaxError:
+                try:
+                    html5lib.parseFragment(self.queue_msg, treebuilder='lxml', namespaceHTMLElements=False)[0]
+                except (IndexError, ValueError):
+                    # If neither can parse queue_msg, it contains invalid xml.
+                    queue_msg = u"<span>{0}</span>".format(_("Error running code."))
+
         extra_context = {
             'queue_len': str(self.queue_len),
-            'queue_msg': self.queue_msg,
+            'queue_msg': queue_msg,
             'button_enabled': self.button_enabled(),
             'matlab_editor_js': '{static_url}js/vendor/CodeMirror/octave.js'.format(
                 static_url=self.capa_system.STATIC_URL),