Properly convert files from Webob to pure files.

Webob represents uploaded files as cgi.FieldStorage objects.  The
XModule code expects pure Python file objects.  Each FieldStorage object
is wrapped to present the proper file interface, with file names.

LMS-1492

common/lib/xmodule/xmodule/tests/test_capa_module.py

@@ -591,7 +591,6 @@ class CapaModuleTest(unittest.TestCase):
         for fpath, fileobj in kwargs['files'].iteritems():
             self.assertEqual(fpath, fileobj.name)
 
-    @unittest.expectedFailure
     def test_check_problem_with_files_as_xblock(self):
         # Check a problem with uploaded files, using the XBlock API.
         # pylint: disable=W0212

common/lib/xmodule/xmodule/tests/test_xblock_wrappers.py

@@ -257,7 +257,7 @@ class TestXModuleHandler(TestXBlockWrapper):
     def setUp(self):
         self.module = XModule(descriptor=Mock(), field_data=Mock(), runtime=Mock(), scope_ids=Mock())
         self.module.handle_ajax = Mock(return_value='{}')
-        self.request = Mock()
+        self.request = webob.Request({})
 
     def test_xmodule_handler_passed_data(self):
         self.module.xmodule_handler(self.request)

common/lib/xmodule/xmodule/x_module.py

@@ -8,6 +8,7 @@ from lxml import etree
 from collections import namedtuple
 from pkg_resources import resource_listdir, resource_string, resource_isdir
 from webob import Response
+from webob.multidict import MultiDict
 
 from xmodule.modulestore import Location
 from xmodule.modulestore.exceptions import ItemNotFoundError, InsufficientSpecificationError, InvalidLocationError
@@ -405,7 +406,31 @@ class XModule(XModuleMixin, HTMLSnippet, XBlock):  # pylint: disable=abstract-me
         """
         XBlock handler that wraps `handle_ajax`
         """
-        response_data = self.handle_ajax(suffix, request.POST)
+        class FileObjForWebobFiles(object):
+            """
+            Turn Webob cgi.FieldStorage uploaded files into pure file objects.
+
+            Webob represents uploaded files as cgi.FieldStorage objects, which
+            have a .file attribute.  We wrap the FieldStorage object, delegating
+            attribute access to the .file attribute.  But the files have no
+            name, so we carry the FieldStorage .filename attribute as the .name.
+
+            """
+            def __init__(self, webob_file):
+                self.file = webob_file.file
+                self.name = webob_file.filename
+
+            def __getattr__(self, name):
+                return getattr(self.file, name)
+
+        # WebOb requests have multiple entries for uploaded files.  handle_ajax
+        # expects a single entry as a list.
+        request_post = MultiDict(request.POST)
+        for key in set(request.POST.iterkeys()):
+            if hasattr(request.POST[key], "file"):
+                request_post[key] = map(FileObjForWebobFiles, request.POST.getall(key))
+
+        response_data = self.handle_ajax(suffix, request_post)
         return Response(response_data, content_type='application/json')
 
     def get_children(self):

requirements/edx/github.txt

@@ -15,7 +15,7 @@
 -e git+https://github.com/eventbrite/zendesk.git@d53fe0e81b623f084e91776bcf6369f8b7b63879#egg=zendesk
 
 # Our libraries:
--e git+https://github.com/edx/XBlock.git@2daa4e54#egg=XBlock
+-e git+https://github.com/edx/XBlock.git@d6d2fc91#egg=XBlock
 -e git+https://github.com/edx/codejail.git@0a1b468#egg=codejail
 -e git+https://github.com/edx/diff-cover.git@v0.2.6#egg=diff_cover
 -e git+https://github.com/edx/js-test-tool.git@v0.1.4#egg=js_test_tool