Remove malformed tags when contents aren't malformed anymore.

common/lib/xmodule/tests/test_import.py

 from path import path
-
 import unittest
 
+from lxml import etree
+
 from xmodule.x_module import XMLParsingSystem, XModuleDescriptor
 from xmodule.errorhandlers import ignore_errors_handler
 from xmodule.modulestore import Location
@@ -61,3 +62,26 @@ class ImportTestCase(unittest.TestCase):
 
         self.assertEqual(descriptor.definition['data'],
                          re_import_descriptor.definition['data'])
+
+    def test_fixed_xml_tag(self):
+        """Make sure a tag that's been fixed exports as the original tag type"""
+
+        # create a malformed tag with valid xml contents
+        root = etree.Element('malformed')
+        good_xml = '''<sequential display_name="fixed"><video url="hi"/></sequential>'''
+        root.text = good_xml
+
+        xml_str_in = etree.tostring(root)
+
+        # load it
+        system = self.get_system()
+        descriptor = XModuleDescriptor.load_from_xml(xml_str_in, system, 'org', 'course',
+                                                     None)
+        # export it
+        resource_fs = None
+        xml_str_out = descriptor.export_to_xml(resource_fs)
+
+        # Now make sure the exported xml is a sequential
+        xml_out = etree.fromstring(xml_str_out)
+        self.assertEqual(xml_out.tag, 'sequential')
+

common/lib/xmodule/xmodule/malformed_module.py

 from pkg_resources import resource_string
 from lxml import etree
+from xmodule.x_module import XModule
 from xmodule.mako_module import MakoModuleDescriptor
 from xmodule.xml_module import XmlDescriptor
 from xmodule.editing_module import EditingDescriptor
@@ -8,10 +9,18 @@ import logging
 
 log = logging.getLogger(__name__)
 
+class MalformedModule(XModule):
+    def get_html(self):
+        '''Show an error.
+        TODO (vshnayder): proper style, divs, etc.
+        '''
+        return "Malformed content--not showing through get_html()"
+
 class MalformedDescriptor(EditingDescriptor):
     """
     Module that provides a raw editing view of broken xml.
     """
+    module_class = MalformedModule
 
     @classmethod
     def from_xml(cls, xml_data, system, org=None, course=None):
@@ -20,8 +29,8 @@ class MalformedDescriptor(EditingDescriptor):
         Does not try to parse the data--just stores it.
         '''
 
-        #log.debug("processing '{0}'".format(xml_data))
         try:
+            # If this is already a malformed tag, don't want to re-wrap it.
             xml_obj = etree.fromstring(xml_data)
             if xml_obj.tag == 'malformed':
                 xml_data = xml_obj.text
@@ -40,9 +49,18 @@ class MalformedDescriptor(EditingDescriptor):
 
     def export_to_xml(self, resource_fs):
         '''
-        Export as a string wrapped in xml
-        '''
-        root = etree.Element('malformed')
-        root.text = self.definition['data']
-        return etree.tostring(root)
+        If the definition data is invalid xml, export it wrapped in a malformed
+        tag.  If it is valid, export without the wrapper.
 
+        NOTE: There may still be problems with the valid xml--it could be
+        missing required attributes, could have the wrong tags, refer to missing
+        files, etc.
+        '''
+        try:
+           xml = etree.fromstring(self.definition['data'])
+           return etree.tostring(xml)
+        except etree.XMLSyntaxError:
+            # still not valid.
+            root = etree.Element('malformed')
+            root.text = self.definition['data']
+            return etree.tostring(root)