Fix split_test import and export.

LMS-2405

common/lib/xmodule/xmodule/course_module.py

@@ -172,12 +172,12 @@ class CourseFields(object):
     textbooks = TextbookList(help="List of pairs of (title, url) for textbooks used in this course",
                              default=[], scope=Scope.content)
 
-    # This field is intended for Studio to update, not to be exposed directly via
-    # advanced_settings.
+    # This is should be scoped to content, but since it's defined in the policy
+    # file, it is currently scoped to settings.
     user_partitions = UserPartitionList(
         help="List of user partitions of this course into groups, used e.g. for experiments",
         default=[],
-        scope=Scope.content
+        scope=Scope.settings
     )
 
     wiki_slug = String(help="Slug that points to the wiki for this course", scope=Scope.content)

common/lib/xmodule/xmodule/split_test_module.py

@@ -3,6 +3,7 @@ Module for running content split tests
 """
 
 import logging
+import json
 from webob import Response
 
 from xmodule.progress import Progress
@@ -251,12 +252,38 @@ class SplitTestDescriptor(SplitTestFields, SequenceDescriptor):
     def definition_to_xml(self, resource_fs):
 
         xml_object = etree.Element('split_test')
-        # TODO: also save the experiment id and the condition map
+        xml_object.set('group_id_to_child', json.dumps(self.group_id_to_child))
+        xml_object.set('user_partition_id', str(self.user_partition_id))
         for child in self.get_children():
-            xml_object.append(
-                etree.fromstring(child.export_to_xml(resource_fs)))
+            self.runtime.add_block_as_child_node(child, xml_object)
         return xml_object
 
+    @classmethod
+    def definition_from_xml(cls, xml_object, system):
+        children = []
+        raw_group_id_to_child = xml_object.attrib.get('group_id_to_child', None)
+        user_partition_id = xml_object.attrib.get('user_partition_id', None)
+        try:
+            group_id_to_child = json.loads(raw_group_id_to_child)
+        except ValueError:
+            msg = "group_id_to_child is not valid json"
+            log.exception(msg)
+            system.error_tracker(msg)
+
+        for child in xml_object:
+            try:
+                descriptor = system.process_xml(etree.tostring(child))
+                children.append(descriptor.scope_ids.usage_id)
+            except Exception:
+                msg = "Unable to load child when parsing split_test module."
+                log.exception(msg)
+                system.error_tracker(msg)
+
+        return ({
+            'group_id_to_child': group_id_to_child,
+            'user_partition_id': user_partition_id
+        }, children)
+
     def has_dynamic_children(self):
         """
         Grading needs to know that only one of the children is actually "real".  This

common/lib/xmodule/xmodule/tests/test_split_module.py

@@ -2,11 +2,14 @@
 Tests for the Split Testing Module
 """
 import ddt
-from mock import Mock
+import lxml
+from mock import Mock, patch
+from fs.memoryfs import MemoryFS
 
 from xmodule.tests.xml import factories as xml
 from xmodule.tests.xml import XModuleXmlImportTest
 from xmodule.tests import get_test_system
+from xmodule.split_test_module import SplitTestDescriptor
 from xmodule.partitions.partitions import Group, UserPartition
 from xmodule.partitions.test_partitions import StaticPartitionService, MemoryUserTagsService
 
@@ -52,6 +55,7 @@ class SplitTestModuleTest(XModuleXmlImportTest):
 
         self.module_system.get_module = get_module
         self.module_system.descriptor_system = self.course.runtime
+        self.course.runtime.export_fs = MemoryFS()
 
         self.tags_service = MemoryUserTagsService()
         self.module_system._services['user_tags'] = self.tags_service  # pylint: disable=protected-access
@@ -120,3 +124,26 @@ class SplitTestModuleTest(XModuleXmlImportTest):
         # So, we check that we get the same url_name when we call on the url_name twice.
         # We run the test ten times so that, if our storage is failing, we'll be most likely to notice it.
         self.assertEquals(self.split_test_module.child_descriptor.url_name, self.split_test_module.child_descriptor.url_name)
+
+    # Patch the definition_to_xml for the html children.
+    @patch('xmodule.html_module.HtmlDescriptor.definition_to_xml')
+    def test_export_import_round_trip(self, def_to_xml):
+        # The HtmlDescriptor definition_to_xml tries to write to the filesystem
+        # before returning an xml object. Patch this to just return the xml.
+        def_to_xml.return_value = lxml.etree.Element('html')
+
+        # Mock out the process_xml
+        # Expect it to return a child descriptor for the SplitTestDescriptor when called.
+        self.module_system.process_xml = Mock()
+
+        # Write out the xml.
+        xml_obj = self.split_test_module.definition_to_xml(MemoryFS())
+
+        self.assertEquals(xml_obj.get('user_partition_id'), '0')
+        self.assertIsNotNone(xml_obj.get('group_id_to_child'))
+
+        # Read the xml back in.
+        fields, children = SplitTestDescriptor.definition_from_xml(xml_obj, self.module_system)
+        self.assertEquals(fields.get('user_partition_id'), '0')
+        self.assertIsNotNone(fields.get('group_id_to_child'))
+        self.assertEquals(len(children), 2)