Merge pull request #5942 from edx/cohorted-courseware

Cohorted courseware

CHANGELOG.rst

@@ -5,6 +5,12 @@ These are notable changes in edx-platform.  This is a rolling list of changes,
 in roughly chronological order, most recent first.  Add your entries at or near
 the top.  Include a label indicating the component affected.
 
+Platform: Add group_access field to all xblocks.  TNL-670
+
+LMS: Add support for user partitioning based on cohort.  TNL-710
+
+Platform: Add base support for cohorted group configurations.  TNL-649
+
 Common: Add configurable reset button to units
 
 Studio: Add support xblock validation messages on Studio unit/container page. TNL-683

cms/djangoapps/contentstore/views/course.py

@@ -22,7 +22,7 @@ from xmodule.error_module import ErrorDescriptor
 from xmodule.modulestore.django import modulestore
 from xmodule.contentstore.content import StaticContent
 from xmodule.tabs import PDFTextbookTabs
-from xmodule.partitions.partitions import UserPartition, Group
+from xmodule.partitions.partitions import UserPartition
 from xmodule.modulestore import EdxJSONEncoder
 from xmodule.modulestore.exceptions import ItemNotFoundError, DuplicateCourseError
 from opaque_keys import InvalidKeyError
@@ -1173,7 +1173,7 @@ class GroupConfiguration(object):
             configuration = json.loads(json_string)
         except ValueError:
             raise GroupConfigurationsValidationError(_("invalid JSON"))
-
+        configuration["version"] = UserPartition.VERSION
         return configuration
 
     def validate(self):
@@ -1224,14 +1224,7 @@ class GroupConfiguration(object):
         """
         Get user partition for saving in course.
         """
-        groups = [Group(g["id"], g["name"]) for g in self.configuration["groups"]]
-
-        return UserPartition(
-            self.configuration["id"],
-            self.configuration["name"],
-            self.configuration["description"],
-            groups
-        )
+        return UserPartition.from_json(self.configuration)
 
     @staticmethod
     def get_usage_info(course, store):
@@ -1345,15 +1338,12 @@ def group_configurations_list_handler(request, course_key_string):
         if 'text/html' in request.META.get('HTTP_ACCEPT', 'text/html'):
             group_configuration_url = reverse_course_url('group_configurations_list_handler', course_key)
             course_outline_url = reverse_course_url('course_handler', course_key)
-            split_test_enabled = SPLIT_TEST_COMPONENT_TYPE in ADVANCED_COMPONENT_TYPES and SPLIT_TEST_COMPONENT_TYPE in course.advanced_modules
-
             configurations = GroupConfiguration.add_usage_info(course, store)
-
             return render_to_response('group_configurations.html', {
                 'context_course': course,
                 'group_configuration_url': group_configuration_url,
                 'course_outline_url': course_outline_url,
-                'configurations': configurations if split_test_enabled else None,
+                'configurations': configurations if should_show_group_configurations_page(course) else None,
             })
         elif "application/json" in request.META.get('HTTP_ACCEPT'):
             if request.method == 'POST':
@@ -1432,6 +1422,16 @@ def group_configurations_detail_handler(request, course_key_string, group_config
             return JsonResponse(status=204)
 
 
+def should_show_group_configurations_page(course):
+    """
+    Returns true if Studio should show the "Group Configurations" page for the specified course.
+    """
+    return (
+        SPLIT_TEST_COMPONENT_TYPE in ADVANCED_COMPONENT_TYPES and
+        SPLIT_TEST_COMPONENT_TYPE in course.advanced_modules
+    )
+
+
 def _get_course_creator_status(user):
     """
     Helper method for returning the course creator status for a particular user,

cms/djangoapps/contentstore/views/tests/test_group_configurations.py

@@ -15,10 +15,17 @@ from xmodule.modulestore import ModuleStoreEnum
 
 GROUP_CONFIGURATION_JSON = {
     u'name': u'Test name',
+    u'scheme': u'random',
     u'description': u'Test description',
+    u'version': UserPartition.VERSION,
     u'groups': [
-        {u'name': u'Group A'},
-        {u'name': u'Group B'},
+        {
+            u'name': u'Group A',
+            u'version': 1,
+        }, {
+            u'name': u'Group B',
+            u'version': 1,
+        },
     ],
 }
 
@@ -229,7 +236,8 @@ class GroupConfigurationsListHandlerTestCase(CourseTestCase, GroupConfigurations
         expected = {
             u'description': u'Test description',
             u'name': u'Test name',
-            u'version': 1,
+            u'scheme': u'random',
+            u'version': UserPartition.VERSION,
             u'groups': [
                 {u'name': u'Group A', u'version': 1},
                 {u'name': u'Group B', u'version': 1},
@@ -279,15 +287,16 @@ class GroupConfigurationsDetailHandlerTestCase(CourseTestCase, GroupConfiguratio
             kwargs={'group_configuration_id': cid},
         )
 
-    def test_can_create_new_group_configuration_if_it_is_not_exist(self):
+    def test_can_create_new_group_configuration_if_it_does_not_exist(self):
         """
         PUT new group configuration when no configurations exist in the course.
         """
         expected = {
             u'id': 999,
             u'name': u'Test name',
+            u'scheme': u'random',
             u'description': u'Test description',
-            u'version': 1,
+            u'version': UserPartition.VERSION,
             u'groups': [
                 {u'id': 0, u'name': u'Group A', u'version': 1},
                 {u'id': 1, u'name': u'Group B', u'version': 1},
@@ -306,12 +315,12 @@ class GroupConfigurationsDetailHandlerTestCase(CourseTestCase, GroupConfiguratio
         self.assertEqual(content, expected)
         self.reload_course()
         # Verify that user_partitions in the course contains the new group configuration.
-        user_partititons = self.course.user_partitions
-        self.assertEqual(len(user_partititons), 1)
-        self.assertEqual(user_partititons[0].name, u'Test name')
-        self.assertEqual(len(user_partititons[0].groups), 2)
-        self.assertEqual(user_partititons[0].groups[0].name, u'Group A')
-        self.assertEqual(user_partititons[0].groups[1].name, u'Group B')
+        user_partitions = self.course.user_partitions
+        self.assertEqual(len(user_partitions), 1)
+        self.assertEqual(user_partitions[0].name, u'Test name')
+        self.assertEqual(len(user_partitions[0].groups), 2)
+        self.assertEqual(user_partitions[0].groups[0].name, u'Group A')
+        self.assertEqual(user_partitions[0].groups[1].name, u'Group B')
 
     def test_can_edit_group_configuration(self):
         """
@@ -323,8 +332,9 @@ class GroupConfigurationsDetailHandlerTestCase(CourseTestCase, GroupConfiguratio
         expected = {
             u'id': self.ID,
             u'name': u'New Test name',
+            u'scheme': u'random',
             u'description': u'New Test description',
-            u'version': 1,
+            u'version': UserPartition.VERSION,
             u'groups': [
                 {u'id': 0, u'name': u'New Group Name', u'version': 1},
                 {u'id': 2, u'name': u'Group C', u'version': 1},
@@ -430,8 +440,9 @@ class GroupConfigurationsUsageInfoTestCase(CourseTestCase, HelperMethods):
         expected = [{
             'id': 0,
             'name': 'Name 0',
+            'scheme': 'random',
             'description': 'Description 0',
-            'version': 1,
+            'version': UserPartition.VERSION,
             'groups': [
                 {'id': 0, 'name': 'Group A', 'version': 1},
                 {'id': 1, 'name': 'Group B', 'version': 1},
@@ -454,8 +465,9 @@ class GroupConfigurationsUsageInfoTestCase(CourseTestCase, HelperMethods):
         expected = [{
             'id': 0,
             'name': 'Name 0',
+            'scheme': 'random',
             'description': 'Description 0',
-            'version': 1,
+            'version': UserPartition.VERSION,
             'groups': [
                 {'id': 0, 'name': 'Group A', 'version': 1},
                 {'id': 1, 'name': 'Group B', 'version': 1},
@@ -469,8 +481,9 @@ class GroupConfigurationsUsageInfoTestCase(CourseTestCase, HelperMethods):
         }, {
             'id': 1,
             'name': 'Name 1',
+            'scheme': 'random',
             'description': 'Description 1',
-            'version': 1,
+            'version': UserPartition.VERSION,
             'groups': [
                 {'id': 0, 'name': 'Group A', 'version': 1},
                 {'id': 1, 'name': 'Group B', 'version': 1},
@@ -495,8 +508,9 @@ class GroupConfigurationsUsageInfoTestCase(CourseTestCase, HelperMethods):
         expected = [{
             'id': 0,
             'name': 'Name 0',
+            'scheme': 'random',
             'description': 'Description 0',
-            'version': 1,
+            'version': UserPartition.VERSION,
             'groups': [
                 {'id': 0, 'name': 'Group A', 'version': 1},
                 {'id': 1, 'name': 'Group B', 'version': 1},

cms/djangoapps/contentstore/views/tests/test_item.py

@@ -223,8 +223,9 @@ class GetItemTest(ItemTest):
         GROUP_CONFIGURATION_JSON = {
             u'id': 0,
             u'name': u'first_partition',
+            u'scheme': u'random',
             u'description': u'First Partition',
-            u'version': 1,
+            u'version': UserPartition.VERSION,
             u'groups': [
                 {u'id': 0, u'name': u'New_NAME_A', u'version': 1},
                 {u'id': 1, u'name': u'New_NAME_B', u'version': 1},

cms/djangoapps/models/settings/course_metadata.py

@@ -32,6 +32,7 @@ class CourseMetadata(object):
         'name',  # from xblock
         'tags',  # from xblock
         'visible_to_staff_only',
+        'group_access',
     ]
 
     @classmethod

cms/envs/common.py

@@ -575,7 +575,7 @@ INSTALLED_APPS = (
     'contentstore',
     'course_creators',
     'student',  # misleading name due to sharing with lms
-    'course_groups',  # not used in cms (yet), but tests run
+    'openedx.core.djangoapps.course_groups',  # not used in cms (yet), but tests run
 
     # Tracking
     'track',
@@ -607,7 +607,7 @@ INSTALLED_APPS = (
     'reverification',
 
     # User preferences
-    'user_api',
+    'openedx.core.djangoapps.user_api',
     'django_openid_auth',
 
     'embargo',

cms/static/js/models/group.js

@@ -7,7 +7,7 @@ define([
         defaults: function() {
             return {
                 name: '',
-                version: null,
+                version: 1,
                 order: null
              };
         },

cms/static/js/models/group_configuration.js

@@ -9,8 +9,9 @@ function(Backbone, _, str, gettext, GroupModel, GroupCollection) {
         defaults: function() {
             return {
                 name: '',
+                scheme: 'random',
                 description: '',
-                version: null,
+                version: 2,
                 groups: new GroupCollection([
                     {
                         name: gettext('Group A'),
@@ -71,6 +72,7 @@ function(Backbone, _, str, gettext, GroupModel, GroupCollection) {
             return {
                 id: this.get('id'),
                 name: this.get('name'),
+                scheme: this.get('scheme'),
                 description: this.get('description'),
                 version: this.get('version'),
                 groups: this.get('groups').toJSON()

cms/static/js/spec/models/group_configuration_spec.js

@@ -99,7 +99,8 @@ define([
                         'id': 10,
                         'name': 'My Group Configuration',
                         'description': 'Some description',
-                        'version': 1,
+                        'version': 2,
+                        'scheme': 'random',
                         'groups': [
                             {
                                 'version': 1,
@@ -114,9 +115,10 @@ define([
                         'id': 10,
                         'name': 'My Group Configuration',
                         'description': 'Some description',
+                        'scheme': 'random',
                         'showGroups': false,
                         'editing': false,
-                        'version': 1,
+                        'version': 2,
                         'groups': [
                             {
                                 'version': 1,

cms/templates/group_configurations.html

@@ -55,7 +55,7 @@
         </div>
       % else:
         <div class="ui-loading">
-            <p><span class="spin"><i class="icon-refresh"></i></span> <span class="copy">${_("Loading...")}</span></p>
+            <p><span class="spin"><i class="icon-refresh"></i></span> <span class="copy">${_("Loading")}</span></p>
         </div>
       % endif
       </article>

cms/templates/settings.html

@@ -7,6 +7,7 @@
 <%!
   from django.utils.translation import ugettext as _
   from contentstore import utils
+  from contentstore.views.course import should_show_group_configurations_page
   import urllib
 %>
 
@@ -312,10 +313,10 @@ CMS.URL.UPLOAD_ASSET = '${upload_asset_url}';
           <ul>
             <li class="nav-item"><a href="${grading_config_url}">${_("Grading")}</a></li>
             <li class="nav-item"><a href="${course_team_url}">${_("Course Team")}</a></li>
+            % if should_show_group_configurations_page(context_course):
+              <li class="nav-item"><a href="${utils.reverse_course_url('group_configurations_list_handler', context_course.id)}">${_("Group Configurations")}</a></li>
+            % endif
             <li class="nav-item"><a href="${advanced_config_url}">${_("Advanced Settings")}</a></li>
-          % if "split_test" in context_course.advanced_modules:
-            <li class="nav-item"><a href="${utils.reverse_course_url('group_configurations_list_handler', context_course.id)}">${_("Group Configurations")}</a></li>
-          % endif
           </ul>
         </nav>
      % endif

cms/templates/settings_advanced.html

@@ -4,6 +4,7 @@
 <%!
   from django.utils.translation import ugettext as _
   from contentstore import utils
+  from contentstore.views.course import should_show_group_configurations_page
   from django.utils.html import escapejs
 %>
 <%block name="title">${_("Advanced Settings")}</%block>
@@ -91,9 +92,9 @@
             <li class="nav-item"><a href="${details_url}">${_("Details &amp; Schedule")}</a></li>
             <li class="nav-item"><a href="${grading_url}">${_("Grading")}</a></li>
             <li class="nav-item"><a href="${course_team_url}">${_("Course Team")}</a></li>
-          % if "split_test" in context_course.advanced_modules:
-            <li class="nav-item"><a href="${utils.reverse_course_url('group_configurations_list_handler', context_course.id)}">${_("Group Configurations")}</a></li>
-          % endif
+            % if should_show_group_configurations_page(context_course):
+              <li class="nav-item"><a href="${utils.reverse_course_url('group_configurations_list_handler', context_course.id)}">${_("Group Configurations")}</a></li>
+            % endif
           </ul>
         </nav>
       % endif

cms/templates/settings_graders.html

@@ -6,6 +6,7 @@
 <%namespace name='static' file='static_content.html'/>
 <%!
   from contentstore import utils
+  from contentstore.views.course import should_show_group_configurations_page
   from django.utils.translation import ugettext as _
 %>
 
@@ -134,10 +135,10 @@
           <ul>
             <li class="nav-item"><a href="${detailed_settings_url}">${_("Details &amp; Schedule")}</a></li>
             <li class="nav-item"><a href="${course_team_url}">${_("Course Team")}</a></li>
+            % if should_show_group_configurations_page(context_course):
+              <li class="nav-item"><a href="${utils.reverse_course_url('group_configurations_list_handler', context_course.id)}">${_("Group Configurations")}</a></li>
+            % endif
             <li class="nav-item"><a href="${advanced_settings_url}">${_("Advanced Settings")}</a></li>
-          % if "split_test" in context_course.advanced_modules:
-            <li class="nav-item"><a href="${utils.reverse_course_url('group_configurations_list_handler', context_course.id)}">${_("Group Configurations")}</a></li>
-          % endif
           </ul>
         </nav>
       % endif

cms/templates/widgets/header.html

@@ -3,6 +3,7 @@
   from django.core.urlresolvers import reverse
   from django.utils.translation import ugettext as _
   from contentstore.context_processors import doc_url
+  from contentstore.views.course import should_show_group_configurations_page
 %>
 <%page args="online_help_token"/>
 
@@ -81,14 +82,14 @@
                   <li class="nav-item nav-course-settings-team">
                     <a href="${course_team_url}">${_("Course Team")}</a>
                   </li>
+                  % if should_show_group_configurations_page(context_course):
+                    <li class="nav-item nav-course-settings-group-configurations">
+                      <a href="${reverse('contentstore.views.group_configurations_list_handler', kwargs={'course_key_string': unicode(course_key)})}">${_("Group Configurations")}</a>
+                    </li>
+                  % endif
                   <li class="nav-item nav-course-settings-advanced">
                     <a href="${advanced_settings_url}">${_("Advanced Settings")}</a>
                   </li>
-                  % if "split_test" in context_course.advanced_modules:
-                  <li class="nav-item nav-course-settings-group-configurations">
-                    <a href="${reverse('contentstore.views.group_configurations_list_handler', kwargs={'course_key_string': unicode(course_key)})}">${_("Group Configurations")}</a>
-                  </li>
-                  % endif
                 </ul>
               </div>
             </div>

cms/urls.py

@@ -39,7 +39,7 @@ urlpatterns = patterns('',  # nopep8
     url(r'^xmodule/', include('pipeline_js.urls')),
     url(r'^heartbeat$', include('heartbeat.urls')),
 
-    url(r'^user_api/', include('user_api.urls')),
+    url(r'^user_api/', include('openedx.core.djangoapps.user_api.urls')),
     url(r'^lang_pref/', include('lang_pref.urls')),
 )
 

common/djangoapps/lang_pref/middleware.py

@@ -2,7 +2,7 @@
 Middleware for Language Preferences
 """
 
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from lang_pref import LANGUAGE_KEY
 
 

common/djangoapps/lang_pref/tests/test_middleware.py

@@ -3,7 +3,7 @@ from django.test.client import RequestFactory
 from django.contrib.sessions.middleware import SessionMiddleware
 
 from lang_pref.middleware import LanguagePreferenceMiddleware
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from lang_pref import LANGUAGE_KEY
 from student.tests.factories import UserFactory
 

common/djangoapps/lang_pref/tests/test_views.py

@@ -4,7 +4,7 @@ Tests for the language setting view
 from django.core.urlresolvers import reverse
 from django.test import TestCase
 from student.tests.factories import UserFactory
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from lang_pref import LANGUAGE_KEY
 
 

common/djangoapps/lang_pref/views.py

@@ -4,7 +4,7 @@ Views for accessing language preferences
 from django.contrib.auth.decorators import login_required
 from django.http import HttpResponse, HttpResponseBadRequest
 
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from lang_pref import LANGUAGE_KEY
 
 

common/djangoapps/student/tests/test_create_account.py

@@ -12,7 +12,7 @@ from django.test import TestCase, TransactionTestCase
 
 import mock
 
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from lang_pref import LANGUAGE_KEY
 
 from edxmako.tests import mako_middleware_process_request

common/djangoapps/student/tests/test_enrollment.py

@@ -106,7 +106,7 @@ class EnrollmentTest(ModuleStoreTestCase):
         self.assertFalse(CourseEnrollment.is_enrolled(self.user, self.course.id))
 
     @patch.dict(settings.FEATURES, {'ENABLE_MKTG_EMAIL_OPT_IN': True})
-    @patch('user_api.api.profile.update_email_opt_in')
+    @patch('openedx.core.djangoapps.user_api.api.profile.update_email_opt_in')
     @ddt.data(
         ([], 'true'),
         ([], 'false'),

common/djangoapps/student/views.py

@@ -79,7 +79,7 @@ import external_auth.views
 from bulk_email.models import Optout, CourseAuthorization
 import shoppingcart
 from shoppingcart.models import DonationConfiguration
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from lang_pref import LANGUAGE_KEY
 
 import track.views
@@ -105,7 +105,7 @@ from student.helpers import (
 )
 from xmodule.error_module import ErrorDescriptor
 from shoppingcart.models import CourseRegistrationCode
-from user_api.api import profile as profile_api
+from openedx.core.djangoapps.user_api.api import profile as profile_api
 
 import analytics
 from eventtracking import tracker

common/lib/xmodule/xmodule/modulestore/inheritance.py

@@ -57,6 +57,15 @@ class InheritanceMixin(XBlockMixin):
         default=False,
         scope=Scope.settings,
     )
+    group_access = Dict(
+        help="A dictionary that maps which groups can be shown this block. The keys "
+             "are group configuration ids and the values are a list of group IDs. "
+             "If there is no key for a group configuration or if the list of group IDs "
+             "is empty then the block is considered visible to all. Note that this "
+             "field is ignored if the block is visible_to_staff_only.",
+        default={},
+        scope=Scope.settings,
+    )
     course_edit_method = String(
         display_name=_("Course Editor"),
         help=_("Enter the method by which this course is edited (\"XML\" or \"Studio\")."),
@@ -142,8 +151,8 @@ class InheritanceMixin(XBlockMixin):
     # 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(
-        display_name=_("Experiment Group Configurations"),
-        help=_("Enter the configurations that govern how students are grouped for content experiments."),
+        display_name=_("Group Configurations"),
+        help=_("Enter the configurations that govern how students are grouped together."),
         default=[],
         scope=Scope.settings
     )

common/lib/xmodule/xmodule/modulestore/tests/test_cross_modulestore_import_export.py

@@ -31,6 +31,7 @@ from xmodule.modulestore.xml_exporter import export_to_xml
 from xmodule.modulestore.split_mongo.split_draft import DraftVersioningModuleStore
 from xmodule.modulestore.tests.mongo_connection import MONGO_PORT_NUM, MONGO_HOST
 from xmodule.modulestore.inheritance import InheritanceMixin
+from xmodule.partitions.tests.test_partitions import PartitionTestCase
 from xmodule.x_module import XModuleMixin
 from xmodule.modulestore.xml import XMLModuleStore
 
@@ -291,7 +292,7 @@ COURSE_DATA_NAMES = (
 
 @ddt.ddt
 @attr('mongo')
-class CrossStoreXMLRoundtrip(CourseComparisonTest):
+class CrossStoreXMLRoundtrip(CourseComparisonTest, PartitionTestCase):
     """
     This class exists to test XML import and export between different modulestore
     classes.

common/lib/xmodule/xmodule/partitions/partitions.py

 """Defines ``Group`` and ``UserPartition`` models for partitioning"""
+
 from collections import namedtuple
+from stevedore.extension import ExtensionManager
+
 # We use ``id`` in this file as the IDs of our Groups and UserPartitions,
 # which Pylint disapproves of.
 # pylint: disable=invalid-name, redefined-builtin
 
 
+class UserPartitionError(Exception):
+    """
+    An error was found regarding user partitions.
+    """
+    pass
+
+
 class Group(namedtuple("Group", "id name")):
     """
     An id and name for a group of students.  The id should be unique
@@ -45,7 +55,7 @@ class Group(namedtuple("Group", "id name")):
         if isinstance(value, Group):
             return value
 
-        for key in ('id', 'name', 'version'):
+        for key in ("id", "name", "version"):
             if key not in value:
                 raise TypeError("Group dict {0} missing value key '{1}'".format(
                     value, key))
@@ -57,21 +67,50 @@ class Group(namedtuple("Group", "id name")):
         return Group(value["id"], value["name"])
 
 
-class UserPartition(namedtuple("UserPartition", "id name description groups")):
+# The Stevedore extension point namespace for user partition scheme plugins.
+USER_PARTITION_SCHEME_NAMESPACE = 'openedx.user_partition_scheme'
+
+
+class UserPartition(namedtuple("UserPartition", "id name description groups scheme")):
     """
     A named way to partition users into groups, primarily intended for running
     experiments.  It is expected that each user will be in at most one group in a
     partition.
 
-    A Partition has an id, name, description, and a list of groups.
+    A Partition has an id, name, scheme, description, and a list of groups.
     The id is intended to be unique within the context where these are used. (e.g. for
-    partitions of users within a course, the ids should be unique per-course)
+    partitions of users within a course, the ids should be unique per-course).
+    The scheme is used to assign users into groups.
     """
-    VERSION = 1
+    VERSION = 2
+
+    # The collection of user partition scheme extensions.
+    scheme_extensions = None
 
-    def __new__(cls, id, name, description, groups):
+    # The default scheme to be used when upgrading version 1 partitions.
+    VERSION_1_SCHEME = "random"
+
+    def __new__(cls, id, name, description, groups, scheme=None, scheme_id=VERSION_1_SCHEME):
         # pylint: disable=super-on-old-class
-        return super(UserPartition, cls).__new__(cls, int(id), name, description, groups)
+        if not scheme:
+            scheme = UserPartition.get_scheme(scheme_id)
+        return super(UserPartition, cls).__new__(cls, int(id), name, description, groups, scheme)
+
+    @staticmethod
+    def get_scheme(name):
+        """
+        Returns the user partition scheme with the given name.
+        """
+        # Note: we're creating the extension manager lazily to ensure that the Python path
+        # has been correctly set up. Trying to create this statically will fail, unfortunately.
+        if not UserPartition.scheme_extensions:
+            UserPartition.scheme_extensions = ExtensionManager(namespace=USER_PARTITION_SCHEME_NAMESPACE)
+        try:
+            scheme = UserPartition.scheme_extensions[name].plugin
+        except KeyError:
+            raise UserPartitionError("Unrecognized scheme {0}".format(name))
+        scheme.name = name
+        return scheme
 
     def to_json(self):
         """
@@ -84,6 +123,7 @@ class UserPartition(namedtuple("UserPartition", "id name description groups")):
         return {
             "id": self.id,
             "name": self.name,
+            "scheme": self.scheme.name,
             "description": self.description,
             "groups": [g.to_json() for g in self.groups],
             "version": UserPartition.VERSION
@@ -102,20 +142,38 @@ class UserPartition(namedtuple("UserPartition", "id name description groups")):
         if isinstance(value, UserPartition):
             return value
 
-        for key in ('id', 'name', 'description', 'version', 'groups'):
+        for key in ("id", "name", "description", "version", "groups"):
             if key not in value:
-                raise TypeError("UserPartition dict {0} missing value key '{1}'"
-                                .format(value, key))
-
-        if value["version"] != UserPartition.VERSION:
-            raise TypeError("UserPartition dict {0} has unexpected version"
-                            .format(value))
+                raise TypeError("UserPartition dict {0} missing value key '{1}'".format(value, key))
+
+        if value["version"] == 1:
+            # If no scheme was provided, set it to the default ('random')
+            scheme_id = UserPartition.VERSION_1_SCHEME
+        elif value["version"] == UserPartition.VERSION:
+            if not "scheme" in value:
+                raise TypeError("UserPartition dict {0} missing value key 'scheme'".format(value))
+            scheme_id = value["scheme"]
+        else:
+            raise TypeError("UserPartition dict {0} has unexpected version".format(value))
 
         groups = [Group.from_json(g) for g in value["groups"]]
+        scheme = UserPartition.get_scheme(scheme_id)
+        if not scheme:
+            raise TypeError("UserPartition dict {0} has unrecognized scheme {1}".format(value, scheme_id))
 
         return UserPartition(
             value["id"],
             value["name"],
             value["description"],
-            groups
+            groups,
+            scheme,
         )
+
+    def get_group(self, group_id):
+        """
+        Returns the group with the specified id.
+        """
+        for group in self.groups:    # pylint: disable=no-member
+            if group.id == group_id:
+                return group
+        return None

common/lib/xmodule/xmodule/partitions/partitions_service.py

@@ -3,7 +3,6 @@ This is a service-like API that assigns tracks which groups users are in for var
 user partitions.  It uses the user_service key/value store provided by the LMS runtime to
 persist the assignments.
 """
-import random
 from abc import ABCMeta, abstractproperty
 
 
@@ -22,13 +21,11 @@ class PartitionService(object):
         """
         raise NotImplementedError('Subclasses must implement course_partition')
 
-    def __init__(self, user_tags_service, course_id, track_function):
-        self.random = random.Random()
-        self._user_tags_service = user_tags_service
-        self._course_id = course_id
+    def __init__(self, runtime, track_function):
+        self.runtime = runtime
         self._track_function = track_function
 
-    def get_user_group_for_partition(self, user_partition_id):
+    def get_user_group_id_for_partition(self, user_partition_id):
         """
         If the user is already assigned to a group in user_partition_id, return the
         group_id.
@@ -53,17 +50,15 @@ class PartitionService(object):
         if user_partition is None:
             raise ValueError(
                 "Configuration problem!  No user_partition with id {0} "
-                "in course {1}".format(user_partition_id, self._course_id)
+                "in course {1}".format(user_partition_id, self.runtime.course_id)
             )
 
-        group_id = self._get_group(user_partition)
-
-        return group_id
+        group = self._get_group(user_partition)
+        return group.id if group else None
 
     def _get_user_partition(self, user_partition_id):
         """
-        Look for a user partition with a matching id in
-        in the course's partitions.
+        Look for a user partition with a matching id in the course's partitions.
 
         Returns:
             A UserPartition, or None if not found.
@@ -74,65 +69,13 @@ class PartitionService(object):
 
         return None
 
-    def _key_for_partition(self, user_partition):
-        """
-        Returns the key to use to look up and save the user's group for a particular
-        condition.  Always use this function rather than constructing the key directly.
-        """
-        return 'xblock.partition_service.partition_{0}'.format(user_partition.id)
-
     def _get_group(self, user_partition):
         """
-        Return the group of the current user in user_partition.  If they don't already have
-        one assigned, pick one and save it.  Uses the runtime's user_service service to look up
-        and persist the info.
+        Returns the group from the specified user partition to which the user is assigned.
+        If the user has not yet been assigned, a group will be chosen for them based upon
+        the partition's scheme.
         """
-        key = self._key_for_partition(user_partition)
-        scope = self._user_tags_service.COURSE_SCOPE
-
-        group_id = self._user_tags_service.get_tag(scope, key)
-        if group_id is not None:
-            group_id = int(group_id)
-
-        partition_group_ids = [group.id for group in user_partition.groups]
-
-        # If a valid group id has been saved already, return it
-        if group_id is not None and group_id in partition_group_ids:
-            return group_id
-
-        # TODO: what's the atomicity of the get above and the save here?  If it's not in a
-        # single transaction, we could get a situation where the user sees one state in one
-        # thread, but then that decision gets overwritten--low probability, but still bad.
-
-        # (If it is truly atomic, we should be fine--if one process is in the
-        # process of finding no group and making one, the other should block till it
-        # appears.  HOWEVER, if we allow reads by the second one while the first
-        # process runs the transaction, we have a problem again: could read empty,
-        # have the first transaction finish, and pick a different group in a
-        # different process.)
-
-        # If a group id hasn't yet been saved, or the saved group id is invalid,
-        # we need to pick one, save it, then return it
-
-        # TODO: had a discussion in arch council about making randomization more
-        # deterministic (e.g. some hash).  Could do that, but need to be careful not
-        # to introduce correlation between users or bias in generation.
-
-        # See note above for explanation of local_random()
-        group = self.random.choice(user_partition.groups)
-        self._user_tags_service.set_tag(scope, key, group.id)
-
-        # emit event for analytics
-        # FYI - context is always user ID that is logged in, NOT the user id that is
-        # being operated on. If instructor can move user explicitly, then we should
-        # put in event_info the user id that is being operated on.
-        event_info = {
-            'group_id': group.id,
-            'group_name': group.name,
-            'partition_id': user_partition.id,
-            'partition_name': user_partition.name
-        }
-        # TODO: Use the XBlock publish api instead
-        self._track_function('xmodule.partitions.assigned_user_to_partition', event_info)
-
-        return group.id
+        user = self.runtime.get_real_user(self.runtime.anonymous_student_id)
+        return user_partition.scheme.get_group_for_user(
+            self.runtime.course_id, user, user_partition, track_function=self._track_function
+        )

common/lib/xmodule/xmodule/split_test_module.py

@@ -80,10 +80,6 @@ class SplitTestFields(object):
     # location needs to actually match one of the children of this
     # Block.  (expected invariant that we'll need to test, and handle
     # authoring tools that mess this up)
-
-    # TODO: is there a way to add some validation around this, to
-    # be run on course load or in studio or ....
-
     group_id_to_child = ReferenceValueDict(
         help=_("Which child module students in a particular group_id should see"),
         scope=Scope.content
@@ -188,7 +184,7 @@ class SplitTestModule(SplitTestFields, XModule, StudioEditableModule):
         partitions_service = self.runtime.service(self, 'partitions')
         if not partitions_service:
             return None
-        return partitions_service.get_user_group_for_partition(self.user_partition_id)
+        return partitions_service.get_user_group_id_for_partition(self.user_partition_id)
 
     @property
     def is_configured(self):

common/lib/xmodule/xmodule/tests/__init__.py

@@ -79,13 +79,15 @@ def get_test_system(course_id=SlashSeparatedCourseKey('org', 'course', 'run')):
     where `my_render_func` is a function of the form my_render_func(template, context).
 
     """
+    user = Mock(is_staff=False)
     return TestModuleSystem(
         static_url='/static',
         track_function=Mock(),
         get_module=Mock(),
         render_template=mock_render_template,
         replace_urls=str,
-        user=Mock(is_staff=False),
+        user=user,
+        get_real_user=lambda(__): user,
         filestore=Mock(),
         debug=True,
         hostname="edx.org",

common/lib/xmodule/xmodule/tests/test_split_test_module.py

@@ -6,6 +6,7 @@ import lxml
 from mock import Mock, patch
 from fs.memoryfs import MemoryFS
 
+from xmodule.partitions.tests.test_partitions import StaticPartitionService, PartitionTestCase, MockUserPartitionScheme
 from xmodule.tests.xml import factories as xml
 from xmodule.tests.xml import XModuleXmlImportTest
 from xmodule.tests import get_test_system
@@ -13,7 +14,6 @@ from xmodule.x_module import AUTHOR_VIEW, STUDENT_VIEW
 from xmodule.validation import StudioValidationMessage
 from xmodule.split_test_module import SplitTestDescriptor, SplitTestFields
 from xmodule.partitions.partitions import Group, UserPartition
-from xmodule.partitions.test_partitions import StaticPartitionService, MemoryUserTagsService
 
 
 class SplitTestModuleFactory(xml.XmlImportFactory):
@@ -23,11 +23,12 @@ class SplitTestModuleFactory(xml.XmlImportFactory):
     tag = 'split_test'
 
 
-class SplitTestModuleTest(XModuleXmlImportTest):
+class SplitTestModuleTest(XModuleXmlImportTest, PartitionTestCase):
     """
     Base class for all split_module tests.
     """
     def setUp(self):
+        super(SplitTestModuleTest, self).setUp()
         self.course_id = 'test_org/test_course_number/test_run'
         # construct module
         course = xml.CourseFactory.build()
@@ -57,16 +58,16 @@ class SplitTestModuleTest(XModuleXmlImportTest):
         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
-
         self.partitions_service = StaticPartitionService(
             [
-                UserPartition(0, 'first_partition', 'First Partition', [Group("0", 'alpha'), Group("1", 'beta')]),
-                UserPartition(1, 'second_partition', 'Second Partition', [Group("0", 'abel'), Group("1", 'baker'), Group("2", 'charlie')])
+                self.user_partition,
+                UserPartition(
+                    1, 'second_partition', 'Second Partition',
+                    [Group("0", 'abel'), Group("1", 'baker'), Group("2", 'charlie')],
+                    MockUserPartitionScheme()
+                )
             ],
-            user_tags_service=self.tags_service,
-            course_id=self.course.id,
+            runtime=self.module_system,
             track_function=Mock(name='track_function'),
         )
         self.module_system._services['partitions'] = self.partitions_service  # pylint: disable=protected-access
@@ -81,50 +82,28 @@ class SplitTestModuleLMSTest(SplitTestModuleTest):
     Test the split test module
     """
 
-    @ddt.data(('0', 'split_test_cond0'), ('1', 'split_test_cond1'))
+    @ddt.data((0, 'split_test_cond0'), (1, 'split_test_cond1'))
     @ddt.unpack
     def test_child(self, user_tag, child_url_name):
-        self.tags_service.set_tag(
-            self.tags_service.COURSE_SCOPE,
-            'xblock.partition_service.partition_0',
-            user_tag
-        )
-
+        self.user_partition.scheme.current_group = self.user_partition.groups[user_tag]    # pylint: disable=no-member
         self.assertEquals(self.split_test_module.child_descriptor.url_name, child_url_name)
 
-    @ddt.data(('0',), ('1',))
-    @ddt.unpack
-    def test_child_old_tag_value(self, _user_tag):
-        # If user_tag has a stale value, we should still get back a valid child url
-        self.tags_service.set_tag(
-            self.tags_service.COURSE_SCOPE,
-            'xblock.partition_service.partition_0',
-            '2'
-        )
-
-        self.assertIn(self.split_test_module.child_descriptor.url_name, ['split_test_cond0', 'split_test_cond1'])
-
-    @ddt.data(('0', 'HTML FOR GROUP 0'), ('1', 'HTML FOR GROUP 1'))
+    @ddt.data((0, 'HTML FOR GROUP 0'), (1, 'HTML FOR GROUP 1'))
     @ddt.unpack
     def test_get_html(self, user_tag, child_content):
-        self.tags_service.set_tag(
-            self.tags_service.COURSE_SCOPE,
-            'xblock.partition_service.partition_0',
-            user_tag
-        )
-
+        self.user_partition.scheme.current_group = self.user_partition.groups[user_tag]    # pylint: disable=no-member
         self.assertIn(
             child_content,
             self.module_system.render(self.split_test_module, STUDENT_VIEW).content
         )
 
-    @ddt.data(('0',), ('1',))
+    @ddt.data((0,), (1,))
     @ddt.unpack
     def test_child_missing_tag_value(self, _user_tag):
         # If user_tag has a missing value, we should still get back a valid child url
         self.assertIn(self.split_test_module.child_descriptor.url_name, ['split_test_cond0', 'split_test_cond1'])
 
-    @ddt.data(('100',), ('200',), ('300',), ('400',), ('500',), ('600',), ('700',), ('800',), ('900',), ('1000',))
+    @ddt.data((100,), (200,), (300,), (400,), (500,), (600,), (700,), (800,), (900,), (1000,))
     @ddt.unpack
     def test_child_persist_new_tag_value_when_tag_missing(self, _user_tag):
         # If a user_tag has a missing value, a group should be saved/persisted for that user.

common/test/acceptance/.coveragerc

 [run]
 data_file = reports/bok_choy/.coverage
 source = lms, cms, common/djangoapps, common/lib
-omit = lms/envs/*, cms/envs/*, common/djangoapps/terrain/*, common/djangoapps/*/migrations/*, */test*, */management/*, */urls*, */wsgi*
+omit = lms/envs/*, cms/envs/*, common/djangoapps/terrain/*, common/djangoapps/*/migrations/*, openedx/core/djangoapps/*/migrations/*, */test*, */management/*, */urls*, */wsgi*
 parallel = True
 
 [report]

lms/.coveragerc

@@ -2,7 +2,7 @@
 [run]
 data_file = reports/lms/.coverage
 source = lms,common/djangoapps
-omit = lms/envs/*, common/djangoapps/terrain/*, common/djangoapps/*/migrations/*
+omit = lms/envs/*, common/djangoapps/terrain/*, common/djangoapps/*/migrations/*, openedx/core/djangoapps/*/migrations/*
 
 [report]
 ignore_errors = True

lms/djangoapps/courseware/tests/test_split_module.py

@@ -12,7 +12,7 @@ from student.tests.factories import UserFactory, CourseEnrollmentFactory
 from xmodule.modulestore.tests.factories import ItemFactory, CourseFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.partitions.partitions import Group, UserPartition
-from user_api.tests.factories import UserCourseTagFactory
+from openedx.core.djangoapps.user_api.tests.factories import UserCourseTagFactory
 
 
 @override_settings(MODULESTORE=TEST_DATA_MOCK_MODULESTORE)

lms/djangoapps/courseware/tests/test_submitting_problems.py

@@ -27,7 +27,7 @@ from student.models import anonymous_id_for_user
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
 from xmodule.partitions.partitions import Group, UserPartition
-from user_api.tests.factories import UserCourseTagFactory
+from openedx.core.djangoapps.user_api.tests.factories import UserCourseTagFactory
 
 
 @override_settings(MODULESTORE=TEST_DATA_MOCK_MODULESTORE)

lms/djangoapps/django_comment_client/forum/tests.py

@@ -6,11 +6,7 @@ from django.http import Http404
 from django.test.client import Client, RequestFactory
 from django.test.utils import override_settings
 from edxmako.tests import mako_middleware_process_request
-from mock import patch, Mock, ANY, call
-from nose.tools import assert_true  # pylint: disable=no-name-in-module
 
-from course_groups.models import CourseUserGroup
-from courseware.courses import UserNotEnrolled
 from django_comment_client.forum import views
 from django_comment_client.tests.group_id import (
     CohortedTopicGroupIdTestMixin,
@@ -21,10 +17,15 @@ from django_comment_client.tests.utils import CohortedContentTestCase
 from django_comment_client.utils import strip_none
 from student.tests.factories import UserFactory, CourseEnrollmentFactory
 from util.testing import UrlResetMixin
-from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
-from xmodule.modulestore.tests.django_utils import TEST_DATA_MOCK_MODULESTORE
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase, TEST_DATA_MOCK_MODULESTORE
 from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
 
+from courseware.courses import UserNotEnrolled
+from nose.tools import assert_true  # pylint: disable=E0611
+from mock import patch, Mock, ANY, call
+
+from openedx.core.djangoapps.course_groups.models import CourseUserGroup
+
 log = logging.getLogger(__name__)
 
 # pylint: disable=missing-docstring

lms/djangoapps/django_comment_client/forum/views.py

@@ -11,7 +11,12 @@ import newrelic.agent
 
 from edxmako.shortcuts import render_to_response
 from courseware.courses import get_course_with_access
-from course_groups.cohorts import is_course_cohorted, get_cohort_id, get_course_cohorts, is_commentable_cohorted
+from openedx.core.djangoapps.course_groups.cohorts import (
+    is_course_cohorted,
+    get_cohort_id,
+    get_course_cohorts,
+    is_commentable_cohorted
+)
 from courseware.access import has_access
 
 from django_comment_client.permissions import cached_has_permission

lms/djangoapps/django_comment_client/tests/group_id.py

 import json
 import re
 
-from course_groups.models import CourseUserGroup
-
 
 class GroupIdAssertionMixin(object):
     def _data_or_params_cs_request(self, mock_request):

lms/djangoapps/django_comment_client/tests/utils.py

 from django.test.utils import override_settings
 from mock import patch
 
-from course_groups.models import CourseUserGroup
+from openedx.core.djangoapps.course_groups.models import CourseUserGroup
 from xmodule.modulestore.tests.django_utils import TEST_DATA_MOCK_MODULESTORE
 from django_comment_common.models import Role
 from django_comment_common.utils import seed_permissions_roles

lms/djangoapps/django_comment_client/utils.py

@@ -17,8 +17,8 @@ from django_comment_client.permissions import check_permissions_by_view, cached_
 from edxmako import lookup_template
 import pystache_custom as pystache
 
-from course_groups.cohorts import get_cohort_by_id, get_cohort_id, is_commentable_cohorted, is_course_cohorted
-from course_groups.models import CourseUserGroup
+from openedx.core.djangoapps.course_groups.cohorts import get_cohort_by_id, get_cohort_id, is_commentable_cohorted, is_course_cohorted
+from openedx.core.djangoapps.course_groups.models import CourseUserGroup
 from opaque_keys.edx.locations import i4xEncoder
 from opaque_keys.edx.keys import CourseKey
 from xmodule.modulestore.django import modulestore

lms/djangoapps/instructor/views/api.py

@@ -62,7 +62,7 @@ import instructor_analytics.basic
 import instructor_analytics.distributions
 import instructor_analytics.csvs
 import csv
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from instructor.views import INVOICE_KEY
 
 from submissions import api as sub_api  # installed from the edx-submissions repository

lms/djangoapps/instructor_analytics/tests/test_basic.py

@@ -2,7 +2,6 @@
 Tests for instructor.basic
 """
 
-from django.test import TestCase
 from student.models import CourseEnrollment
 from django.core.urlresolvers import reverse
 from mock import patch
@@ -17,12 +16,10 @@ from instructor_analytics.basic import (
     sale_record_features, sale_order_record_features, enrolled_students_features, course_registration_features,
     coupon_codes_features, AVAILABLE_FEATURES, STUDENT_FEATURES, PROFILE_FEATURES
 )
-from course_groups.tests.helpers import CohortFactory
-from course_groups.models import CourseUserGroup
+from openedx.core.djangoapps.course_groups.tests.helpers import CohortFactory
 from courseware.tests.factories import InstructorFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory
-from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 
 
 class TestAnalyticsBasic(ModuleStoreTestCase):

lms/djangoapps/instructor_task/tests/test_integration.py

@@ -17,7 +17,7 @@ from django.core.urlresolvers import reverse
 
 from capa.tests.response_xml_factory import (CodeResponseXMLFactory,
                                              CustomResponseXMLFactory)
-from user_api.tests.factories import UserCourseTagFactory
+from openedx.core.djangoapps.user_api.tests.factories import UserCourseTagFactory
 from xmodule.modulestore.tests.factories import ItemFactory
 from xmodule.modulestore import ModuleStoreEnum
 from xmodule.partitions.partitions import Group, UserPartition

lms/djangoapps/notification_prefs/features/unsubscribe.py

 from django.contrib.auth.models import User
 from lettuce import step, world
 from notification_prefs import NOTIFICATION_PREF_KEY
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 
 
 USERNAME = "robot"

lms/djangoapps/notification_prefs/tests.py

@@ -12,7 +12,7 @@ from notification_prefs import NOTIFICATION_PREF_KEY
 from notification_prefs.views import ajax_enable, ajax_disable, ajax_status, set_subscription, UsernameCipher
 from student.tests.factories import UserFactory
 from edxmako.tests import mako_middleware_process_request
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from util.testing import UrlResetMixin
 
 

lms/djangoapps/notification_prefs/views.py

@@ -12,7 +12,7 @@ from django.views.decorators.http import require_GET, require_POST
 
 from edxmako.shortcuts import render_to_response
 from notification_prefs import NOTIFICATION_PREF_KEY
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 
 
 class UsernameDecryptionException(Exception):

lms/djangoapps/notifier_api/serializers.py

@@ -2,7 +2,7 @@ from django.contrib.auth.models import User
 from django.http import Http404
 from rest_framework import serializers
 
-from course_groups.cohorts import is_course_cohorted
+from openedx.core.djangoapps.course_groups.cohorts import is_course_cohorted
 from notification_prefs import NOTIFICATION_PREF_KEY
 from lang_pref import LANGUAGE_KEY
 

lms/djangoapps/notifier_api/tests.py

@@ -5,7 +5,7 @@ from django.conf import settings
 from django.test.client import RequestFactory
 from django.test.utils import override_settings
 
-from course_groups.models import CourseUserGroup
+from openedx.core.djangoapps.course_groups.models import CourseUserGroup
 from django_comment_common.models import Role, Permission
 from lang_pref import LANGUAGE_KEY
 from notification_prefs import NOTIFICATION_PREF_KEY
@@ -13,8 +13,8 @@ from notifier_api.views import NotifierUsersViewSet
 from opaque_keys.edx.locator import CourseLocator
 from student.models import CourseEnrollment
 from student.tests.factories import UserFactory, CourseEnrollmentFactory
-from user_api.models import UserPreference
-from user_api.tests.factories import UserPreferenceFactory
+from openedx.core.djangoapps.user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.tests.factories import UserPreferenceFactory
 from util.testing import UrlResetMixin
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory

lms/djangoapps/notifier_api/views.py

@@ -3,7 +3,7 @@ from rest_framework.viewsets import ReadOnlyModelViewSet
 
 from notification_prefs import NOTIFICATION_PREF_KEY
 from notifier_api.serializers import NotifierUserSerializer
-from user_api.views import ApiKeyHeaderPermission
+from openedx.core.djangoapps.user_api.views import ApiKeyHeaderPermission
 
 
 class NotifierUsersViewSet(ReadOnlyModelViewSet):

lms/djangoapps/oauth2_handler/handlers.py

@@ -6,7 +6,7 @@ from django.core.cache import cache
 from courseware.access import has_access
 from student.models import anonymous_id_for_user
 from student.models import UserProfile
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from lang_pref import LANGUAGE_KEY
 from xmodule.modulestore.django import modulestore
 from xmodule.course_module import CourseDescriptor

lms/djangoapps/oauth2_handler/tests.py

@@ -9,7 +9,7 @@ from student.models import anonymous_id_for_user
 from student.models import UserProfile
 from student.roles import CourseStaffRole, CourseInstructorRole
 from student.tests.factories import UserFactory, UserProfileFactory
-from user_api.models import UserPreference
+from openedx.core.djangoapps.user_api.models import UserPreference
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 
 # Will also run default tests for IDTokens and UserInfo

lms/djangoapps/student_account/test/test_views.py

@@ -16,9 +16,8 @@ from django.test.utils import override_settings
 
 from util.testing import UrlResetMixin
 from third_party_auth.tests.testutil import simulate_running_pipeline
-from user_api.api import account as account_api
-from user_api.api import profile as profile_api
-from util.bad_request_rate_limiter import BadRequestRateLimiter
+from openedx.core.djangoapps.user_api.api import account as account_api
+from openedx.core.djangoapps.user_api.api import profile as profile_api
 from xmodule.modulestore.tests.django_utils import (
     ModuleStoreTestCase, mixed_store_config
 )

lms/djangoapps/student_account/views.py

@@ -16,8 +16,8 @@ from edxmako.shortcuts import render_to_response, render_to_string
 from microsite_configuration import microsite
 import third_party_auth
 
-from user_api.api import account as account_api
-from user_api.api import profile as profile_api
+from openedx.core.djangoapps.user_api.api import account as account_api
+from openedx.core.djangoapps.user_api.api import profile as profile_api
 from util.bad_request_rate_limiter import BadRequestRateLimiter
 
 from student_account.helpers import auth_pipeline_urls

lms/djangoapps/student_profile/test/test_views.py

@@ -11,8 +11,8 @@ from django.conf import settings
 from django.core.urlresolvers import reverse
 
 from util.testing import UrlResetMixin
-from user_api.api import account as account_api
-from user_api.api import profile as profile_api
+from openedx.core.djangoapps.user_api.api import account as account_api
+from openedx.core.djangoapps.user_api.api import profile as profile_api
 from lang_pref import LANGUAGE_KEY, api as language_api
 
 

lms/djangoapps/student_profile/views.py

@@ -11,7 +11,7 @@ from django.views.decorators.http import require_http_methods
 from django_future.csrf import ensure_csrf_cookie
 from django.contrib.auth.decorators import login_required
 from edxmako.shortcuts import render_to_response
-from user_api.api import profile as profile_api
+from openedx.core.djangoapps.user_api.api import profile as profile_api
 from lang_pref import LANGUAGE_KEY, api as language_api
 import third_party_auth
 

lms/envs/common.py

@@ -931,7 +931,7 @@ MIDDLEWARE_CLASSES = (
 
     # Adds user tags to tracking events
     # Must go before TrackMiddleware, to get the context set up
-    'user_api.middleware.UserTagsEventContextMiddleware',
+    'openedx.core.djangoapps.user_api.middleware.UserTagsEventContextMiddleware',
 
     'django.contrib.messages.middleware.MessageMiddleware',
     'track.middleware.TrackMiddleware',
@@ -1438,7 +1438,7 @@ INSTALLED_APPS = (
     'open_ended_grading',
     'psychometrics',
     'licenses',
-    'course_groups',
+    'openedx.core.djangoapps.course_groups',
     'bulk_email',
 
     # External auth (OpenID, shib)
@@ -1482,7 +1482,7 @@ INSTALLED_APPS = (
 
     # User API
     'rest_framework',
-    'user_api',
+    'openedx.core.djangoapps.user_api',
 
     # Shopping cart
     'shoppingcart',

lms/lib/xblock/mixin.py

 """
 Namespace that defines fields common to all blocks used in the LMS
 """
-from xblock.fields import Boolean, Scope, String, XBlockMixin
+from xblock.fields import Boolean, Scope, String, XBlockMixin, Dict
+from xblock.validation import ValidationMessage
+from xmodule.modulestore.inheritance import UserPartitionList
 
 # Make '_' a no-op so we can scrape strings
 _ = lambda text: text
@@ -53,3 +55,73 @@ class LmsBlockMixin(XBlockMixin):
         default=False,
         scope=Scope.settings,
     )
+    group_access = Dict(
+        help="A dictionary that maps which groups can be shown this block. The keys "
+             "are group configuration ids and the values are a list of group IDs. "
+             "If there is no key for a group configuration or if the list of group IDs "
+             "is empty then the block is considered visible to all. Note that this "
+             "field is ignored if the block is visible_to_staff_only.",
+        default={},
+        scope=Scope.settings,
+    )
+
+    # Specified here so we can see what the value set at the course-level is.
+    user_partitions = UserPartitionList(
+        help=_("The list of group configurations for partitioning students in content experiments."),
+        default=[],
+        scope=Scope.settings
+    )
+
+    def _get_user_partition(self, user_partition_id):
+        """
+        Returns the user partition with the specified id, or None if there is no such partition.
+        """
+        for user_partition in self.user_partitions:
+            if user_partition.id == user_partition_id:
+                return user_partition
+
+        return None
+
+    def is_visible_to_group(self, user_partition, group):
+        """
+        Returns true if this xblock should be shown to a user in the specified user partition group.
+        This method returns true if one of the following is true:
+         - the xblock has no group_access dictionary specified
+         - if the dictionary has no key for the user partition's id
+         - if the value for the user partition's id is an empty list
+         - if the value for the user partition's id contains the specified group's id
+        """
+        if not self.group_access:
+            return True
+        group_ids = self.group_access.get(user_partition.id, [])
+        if len(group_ids) == 0:
+            return True
+        return group.id in group_ids
+
+    def validate(self):
+        """
+        Validates the state of this xblock instance.
+        """
+        _ = self.runtime.service(self, "i18n").ugettext  # pylint: disable=redefined-outer-name
+        validation = super(LmsBlockMixin, self).validate()
+        for user_partition_id, group_ids in self.group_access.iteritems():
+            user_partition = self._get_user_partition(user_partition_id)
+            if not user_partition:
+                validation.add(
+                    ValidationMessage(
+                        ValidationMessage.ERROR,
+                        _(u"This xblock refers to a deleted or invalid content group configuration.")
+                    )
+                )
+            else:
+                for group_id in group_ids:
+                    group = user_partition.get_group(group_id)
+                    if not group:
+                        validation.add(
+                            ValidationMessage(
+                                ValidationMessage.ERROR,
+                                _(u"This xblock refers to a deleted or invalid content group.")
+                            )
+                        )
+
+        return validation

lms/lib/xblock/runtime.py

@@ -7,7 +7,7 @@ import xblock.reference.plugins
 
 from django.core.urlresolvers import reverse
 from django.conf import settings
-from user_api.api import course_tag as user_course_tag_api
+from openedx.core.djangoapps.user_api.api import course_tag as user_course_tag_api
 from xmodule.modulestore.django import modulestore
 from xmodule.x_module import ModuleSystem
 from xmodule.partitions.partitions_service import PartitionService
@@ -128,13 +128,13 @@ class LmsPartitionService(PartitionService):
     course.
 
     (If and when XBlock directly provides access from one block (e.g. a split_test_module)
-    to another (e.g. a course_module), this won't be neccessary, but for now it seems like
+    to another (e.g. a course_module), this won't be necessary, but for now it seems like
     the least messy way to hook things through)
 
     """
     @property
     def course_partitions(self):
-        course = modulestore().get_course(self._course_id)
+        course = modulestore().get_course(self.runtime.course_id)
         return course.user_partitions
 
 
@@ -194,8 +194,7 @@ class LmsModuleSystem(LmsHandlerUrls, ModuleSystem):  # pylint: disable=abstract
         services = kwargs.setdefault('services', {})
         services['user_tags'] = UserTagsService(self)
         services['partitions'] = LmsPartitionService(
-            user_tags_service=services['user_tags'],
-            course_id=kwargs.get('course_id', None),
+            runtime=self,
             track_function=kwargs.get('track_function', None),
         )
         services['fs'] = xblock.reference.plugins.FSService()

lms/lib/xblock/test/test_mixin.py

+"""
+Tests of the LMS XBlock Mixin
+"""
+
+from xblock.validation import ValidationMessage
+from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.partitions.partitions import Group, UserPartition
+
+
+class LmsXBlockMixinTestCase(ModuleStoreTestCase):
+    """
+    Base class for XBlock mixin tests cases. A simple course with a single user partition is created
+    in setUp for all subclasses to use.
+    """
+
+    def setUp(self):
+        super(LmsXBlockMixinTestCase, self).setUp()
+        self.user_partition = UserPartition(
+            0,
+            'first_partition',
+            'First Partition',
+            [
+                Group(0, 'alpha'),
+                Group(1, 'beta')
+            ]
+        )
+        self.group1 = self.user_partition.groups[0]    # pylint: disable=no-member
+        self.group2 = self.user_partition.groups[1]    # pylint: disable=no-member
+        self.course = CourseFactory.create(user_partitions=[self.user_partition])
+        self.section = ItemFactory.create(parent=self.course, category='chapter', display_name='Test Section')
+        self.subsection = ItemFactory.create(parent=self.section, category='sequential', display_name='Test Subsection')
+        self.vertical = ItemFactory.create(parent=self.subsection, category='vertical', display_name='Test Unit')
+        self.video = ItemFactory.create(parent=self.subsection, category='video', display_name='Test Video')
+
+
+class XBlockValidationTest(LmsXBlockMixinTestCase):
+    """
+    Unit tests for XBlock validation
+    """
+
+    def verify_validation_message(self, message, expected_message, expected_message_type):
+        """
+        Verify that the validation message has the expected validation message and type.
+        """
+        self.assertEqual(message.text, expected_message)
+        self.assertEqual(message.type, expected_message_type)
+
+    def test_validate_full_group_access(self):
+        """
+        Test the validation messages produced for an xblock with full group access.
+        """
+        validation = self.video.validate()
+        self.assertEqual(len(validation.messages), 0)
+
+    def test_validate_restricted_group_access(self):
+        """
+        Test the validation messages produced for an xblock with a valid group access restriction
+        """
+        self.video.group_access[self.user_partition.id] = [self.group1.id, self.group2.id]  # pylint: disable=no-member
+        validation = self.video.validate()
+        self.assertEqual(len(validation.messages), 0)
+
+    def test_validate_invalid_user_partition(self):
+        """
+        Test the validation messages produced for an xblock referring to a non-existent user partition.
+        """
+        self.video.group_access[999] = [self.group1.id]
+        validation = self.video.validate()
+        self.assertEqual(len(validation.messages), 1)
+        self.verify_validation_message(
+            validation.messages[0],
+            u"This xblock refers to a deleted or invalid content group configuration.",
+            ValidationMessage.ERROR,
+        )
+
+    def test_validate_invalid_group(self):
+        """
+        Test the validation messages produced for an xblock referring to a non-existent group.
+        """
+        self.video.group_access[self.user_partition.id] = [self.group1.id, 999]    # pylint: disable=no-member
+        validation = self.video.validate()
+        self.assertEqual(len(validation.messages), 1)
+        self.verify_validation_message(
+            validation.messages[0],
+            u"This xblock refers to a deleted or invalid content group.",
+            ValidationMessage.ERROR,
+        )
+
+
+class XBlockGroupAccessTest(LmsXBlockMixinTestCase):
+    """
+    Unit tests for XBlock group access.
+    """
+
+    def test_is_visible_to_group(self):
+        """
+        Test the behavior of is_visible_to_group.
+        """
+        # All groups are visible for an unrestricted xblock
+        self.assertTrue(self.video.is_visible_to_group(self.user_partition, self.group1))
+        self.assertTrue(self.video.is_visible_to_group(self.user_partition, self.group2))
+
+        # Verify that all groups are visible if the set of group ids is empty
+        self.video.group_access[self.user_partition.id] = []    # pylint: disable=no-member
+        self.assertTrue(self.video.is_visible_to_group(self.user_partition, self.group1))
+        self.assertTrue(self.video.is_visible_to_group(self.user_partition, self.group2))
+
+        # Verify that only specified groups are visible
+        self.video.group_access[self.user_partition.id] = [self.group1.id]    # pylint: disable=no-member
+        self.assertTrue(self.video.is_visible_to_group(self.user_partition, self.group1))
+        self.assertFalse(self.video.is_visible_to_group(self.user_partition, self.group2))
+
+        # Verify that having an invalid user partition does not affect group visibility of other partitions
+        self.video.group_access[999] = [self.group1.id]
+        self.assertTrue(self.video.is_visible_to_group(self.user_partition, self.group1))
+        self.assertFalse(self.video.is_visible_to_group(self.user_partition, self.group2))
+
+        # Verify that group access is still correct even with invalid group ids
+        self.video.group_access.clear()
+        self.video.group_access[self.user_partition.id] = [self.group2.id, 999]    # pylint: disable=no-member
+        self.assertFalse(self.video.is_visible_to_group(self.user_partition, self.group1))
+        self.assertTrue(self.video.is_visible_to_group(self.user_partition, self.group2))

lms/urls.py

@@ -60,7 +60,7 @@ urlpatterns = ('',  # nopep8
 
     url(r'^heartbeat$', include('heartbeat.urls')),
 
-    url(r'^user_api/', include('user_api.urls')),
+    url(r'^user_api/', include('openedx.core.djangoapps.user_api.urls')),
 
     url(r'^notifier_api/', include('notifier_api.urls')),
 
@@ -343,21 +343,21 @@ if settings.COURSEWARE_ENABLED:
 
         # Cohorts management
         url(r'^courses/{}/cohorts$'.format(settings.COURSE_KEY_PATTERN),
-            'course_groups.views.list_cohorts', name="cohorts"),
+            'openedx.core.djangoapps.course_groups.views.list_cohorts', name="cohorts"),
         url(r'^courses/{}/cohorts/add$'.format(settings.COURSE_KEY_PATTERN),
-            'course_groups.views.add_cohort',
+            'openedx.core.djangoapps.course_groups.views.add_cohort',
             name="add_cohort"),
         url(r'^courses/{}/cohorts/(?P<cohort_id>[0-9]+)$'.format(settings.COURSE_KEY_PATTERN),
-            'course_groups.views.users_in_cohort',
+            'openedx.core.djangoapps.course_groups.views.users_in_cohort',
             name="list_cohort"),
         url(r'^courses/{}/cohorts/(?P<cohort_id>[0-9]+)/add$'.format(settings.COURSE_KEY_PATTERN),
-            'course_groups.views.add_users_to_cohort',
+            'openedx.core.djangoapps.course_groups.views.add_users_to_cohort',
             name="add_to_cohort"),
         url(r'^courses/{}/cohorts/(?P<cohort_id>[0-9]+)/delete$'.format(settings.COURSE_KEY_PATTERN),
-            'course_groups.views.remove_user_from_cohort',
+            'openedx.core.djangoapps.course_groups.views.remove_user_from_cohort',
             name="remove_from_cohort"),
         url(r'^courses/{}/cohorts/debug$'.format(settings.COURSE_KEY_PATTERN),
-            'course_groups.views.debug_cohort_mgmt',
+            'openedx.core.djangoapps.course_groups.views.debug_cohort_mgmt',
             name="debug_cohort_mgmt"),
 
         # Open Ended Notifications

openedx/__init__.py

+"""
+This is the root package for Open edX. The intent is that all importable code
+from Open edX will eventually live here, including the code in the lms, cms,
+and common directories.
+
+Note: for now the code is not structured like this, and hence legacy code will
+continue to live in a number of different packages. All new code should be
+created in this package, and the legacy code will be moved here gradually.
+"""

openedx/core/__init__.py

+"""
+This is the root package for all core Open edX functionality. In particular,
+the djangoapps subpackage is the location for all Django apps that are shared
+between LMS and CMS.
+
+Note: the majority of the core functionality currently lives in the root
+common directory. All new Django apps should be created here instead, and
+the pre-existing apps will be moved here over time.
+"""

common/djangoapps/course_groups/cohorts.py → openedx/core/djangoapps/course_groups/cohorts.py

@@ -14,7 +14,7 @@ from django.utils.translation import ugettext as _
 from courseware import courses
 from eventtracking import tracker
 from student.models import get_user_by_username_or_email
-from .models import CourseUserGroup
+from .models import CourseUserGroup, CourseUserGroupPartitionGroup
 
 log = logging.getLogger(__name__)
 
@@ -373,3 +373,17 @@ def add_user_to_cohort(cohort, username_or_email):
     )
     cohort.users.add(user)
     return (user, previous_cohort_name)
+
+
+def get_partition_group_id_for_cohort(cohort):
+    """
+    Get the ids of the partition and group to which this cohort has been linked
+    as a tuple of (int, int).
+
+    If the cohort has not been linked to any partition/group, both values in the
+    tuple will be None.
+    """
+    res = CourseUserGroupPartitionGroup.objects.filter(course_user_group=cohort)
+    if len(res):
+        return res[0].partition_id, res[0].group_id
+    return None, None

openedx/core/djangoapps/course_groups/migrations/0001_initial.py

+# -*- coding: utf-8 -*-
+import datetime
+from south.db import db
+from south.v2 import SchemaMigration
+from django.db import models, connection
+
+
+class Migration(SchemaMigration):
+
+    def forwards(self, orm):
+        # Adding model 'CourseUserGroup'
+
+        def table_exists(name):
+            return name in connection.introspection.table_names()
+
+        def index_exists(table_name, column_name):
+            return column_name in connection.introspection.get_indexes(connection.cursor(), table_name)
+
+        # Since this djangoapp has been converted to south migrations after-the-fact,
+        # these tables/indexes should already exist when migrating an existing installation.
+        if not (
+            table_exists('course_groups_courseusergroup') and
+            index_exists('course_groups_courseusergroup', 'name') and
+            index_exists('course_groups_courseusergroup', 'course_id') and
+            table_exists('course_groups_courseusergroup_users') and
+            index_exists('course_groups_courseusergroup_users', 'courseusergroup_id') and
+            index_exists('course_groups_courseusergroup_users', 'user_id')
+        ):
+            db.create_table('course_groups_courseusergroup', (
+                ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)),
+                ('name', self.gf('django.db.models.fields.CharField')(max_length=255)),
+                ('course_id', self.gf('xmodule_django.models.CourseKeyField')(max_length=255, db_index=True)),
+                ('group_type', self.gf('django.db.models.fields.CharField')(max_length=20)),
+            ))
+            db.send_create_signal('course_groups', ['CourseUserGroup'])
+
+            # Adding unique constraint on 'CourseUserGroup', fields ['name', 'course_id']
+            db.create_unique('course_groups_courseusergroup', ['name', 'course_id'])
+
+            # Adding M2M table for field users on 'CourseUserGroup'
+            db.create_table('course_groups_courseusergroup_users', (
+                ('id', models.AutoField(verbose_name='ID', primary_key=True, auto_created=True)),
+                ('courseusergroup', models.ForeignKey(orm['course_groups.courseusergroup'], null=False)),
+                ('user', models.ForeignKey(orm['auth.user'], null=False))
+            ))
+            db.create_unique('course_groups_courseusergroup_users', ['courseusergroup_id', 'user_id'])
+
+    def backwards(self, orm):
+        # Removing unique constraint on 'CourseUserGroup', fields ['name', 'course_id']
+        db.delete_unique('course_groups_courseusergroup', ['name', 'course_id'])
+
+        # Deleting model 'CourseUserGroup'
+        db.delete_table('course_groups_courseusergroup')
+
+        # Removing M2M table for field users on 'CourseUserGroup'
+        db.delete_table('course_groups_courseusergroup_users')
+
+    models = {
+        'auth.group': {
+            'Meta': {'object_name': 'Group'},
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '80'}),
+            'permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'})
+        },
+        'auth.permission': {
+            'Meta': {'ordering': "('content_type__app_label', 'content_type__model', 'codename')", 'unique_together': "(('content_type', 'codename'),)", 'object_name': 'Permission'},
+            'codename': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'content_type': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['contenttypes.ContentType']"}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '50'})
+        },
+        'auth.user': {
+            'Meta': {'object_name': 'User'},
+            'date_joined': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'email': ('django.db.models.fields.EmailField', [], {'max_length': '75', 'blank': 'True'}),
+            'first_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'groups': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Group']", 'symmetrical': 'False', 'blank': 'True'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'is_active': ('django.db.models.fields.BooleanField', [], {'default': 'True'}),
+            'is_staff': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'is_superuser': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'last_login': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'last_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'password': ('django.db.models.fields.CharField', [], {'max_length': '128'}),
+            'user_permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'}),
+            'username': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '30'})
+        },
+        'contenttypes.contenttype': {
+            'Meta': {'ordering': "('name',)", 'unique_together': "(('app_label', 'model'),)", 'object_name': 'ContentType', 'db_table': "'django_content_type'"},
+            'app_label': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'model': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '100'})
+        },
+        'course_groups.courseusergroup': {
+            'Meta': {'unique_together': "(('name', 'course_id'),)", 'object_name': 'CourseUserGroup'},
+            'course_id': ('xmodule_django.models.CourseKeyField', [], {'max_length': '255', 'db_index': 'True'}),
+            'group_type': ('django.db.models.fields.CharField', [], {'max_length': '20'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '255'}),
+            'users': ('django.db.models.fields.related.ManyToManyField', [], {'db_index': 'True', 'related_name': "'course_groups'", 'symmetrical': 'False', 'to': "orm['auth.User']"})
+        }
+    }
+
+    complete_apps = ['course_groups']

openedx/core/djangoapps/course_groups/migrations/0002_add_model_CourseUserGroupPartitionGroup.py

+# -*- coding: utf-8 -*-
+import datetime
+from south.db import db
+from south.v2 import SchemaMigration
+from django.db import models
+
+
+class Migration(SchemaMigration):
+
+    def forwards(self, orm):
+        # Adding model 'CourseUserGroupPartitionGroup'
+        db.create_table('course_groups_courseusergrouppartitiongroup', (
+            ('id', self.gf('django.db.models.fields.AutoField')(primary_key=True)),
+            ('course_user_group', self.gf('django.db.models.fields.related.OneToOneField')(to=orm['course_groups.CourseUserGroup'], unique=True)),
+            ('partition_id', self.gf('django.db.models.fields.IntegerField')()),
+            ('group_id', self.gf('django.db.models.fields.IntegerField')()),
+            ('created_at', self.gf('django.db.models.fields.DateTimeField')(auto_now_add=True, blank=True)),
+            ('updated_at', self.gf('django.db.models.fields.DateTimeField')(auto_now=True, blank=True)),
+        ))
+        db.send_create_signal('course_groups', ['CourseUserGroupPartitionGroup'])
+
+    def backwards(self, orm):
+        # Deleting model 'CourseUserGroupPartitionGroup'
+        db.delete_table('course_groups_courseusergrouppartitiongroup')
+
+    models = {
+        'auth.group': {
+            'Meta': {'object_name': 'Group'},
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '80'}),
+            'permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'})
+        },
+        'auth.permission': {
+            'Meta': {'ordering': "('content_type__app_label', 'content_type__model', 'codename')", 'unique_together': "(('content_type', 'codename'),)", 'object_name': 'Permission'},
+            'codename': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'content_type': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['contenttypes.ContentType']"}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '50'})
+        },
+        'auth.user': {
+            'Meta': {'object_name': 'User'},
+            'date_joined': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'email': ('django.db.models.fields.EmailField', [], {'max_length': '75', 'blank': 'True'}),
+            'first_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'groups': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Group']", 'symmetrical': 'False', 'blank': 'True'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'is_active': ('django.db.models.fields.BooleanField', [], {'default': 'True'}),
+            'is_staff': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'is_superuser': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'last_login': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'last_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'password': ('django.db.models.fields.CharField', [], {'max_length': '128'}),
+            'user_permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'}),
+            'username': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '30'})
+        },
+        'contenttypes.contenttype': {
+            'Meta': {'ordering': "('name',)", 'unique_together': "(('app_label', 'model'),)", 'object_name': 'ContentType', 'db_table': "'django_content_type'"},
+            'app_label': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'model': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '100'})
+        },
+        'course_groups.courseusergroup': {
+            'Meta': {'unique_together': "(('name', 'course_id'),)", 'object_name': 'CourseUserGroup'},
+            'course_id': ('xmodule_django.models.CourseKeyField', [], {'max_length': '255', 'db_index': 'True'}),
+            'group_type': ('django.db.models.fields.CharField', [], {'max_length': '20'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '255'}),
+            'users': ('django.db.models.fields.related.ManyToManyField', [], {'db_index': 'True', 'related_name': "'course_groups'", 'symmetrical': 'False', 'to': "orm['auth.User']"})
+        },
+        'course_groups.courseusergrouppartitiongroup': {
+            'Meta': {'object_name': 'CourseUserGroupPartitionGroup'},
+            'course_user_group': ('django.db.models.fields.related.OneToOneField', [], {'to': "orm['course_groups.CourseUserGroup']", 'unique': 'True'}),
+            'created_at': ('django.db.models.fields.DateTimeField', [], {'auto_now_add': 'True', 'blank': 'True'}),
+            'group_id': ('django.db.models.fields.IntegerField', [], {}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'partition_id': ('django.db.models.fields.IntegerField', [], {}),
+            'updated_at': ('django.db.models.fields.DateTimeField', [], {'auto_now': 'True', 'blank': 'True'})
+        }
+    }
+
+    complete_apps = ['course_groups']

common/djangoapps/course_groups/models.py → openedx/core/djangoapps/course_groups/models.py

@@ -35,3 +35,17 @@ class CourseUserGroup(models.Model):
     COHORT = 'cohort'
     GROUP_TYPE_CHOICES = ((COHORT, 'Cohort'),)
     group_type = models.CharField(max_length=20, choices=GROUP_TYPE_CHOICES)
+
+
+class CourseUserGroupPartitionGroup(models.Model):
+    """
+    """
+    course_user_group = models.OneToOneField(CourseUserGroup)
+    partition_id = models.IntegerField(
+        help_text="contains the id of a cohorted partition in this course"
+    )
+    group_id = models.IntegerField(
+        help_text="contains the id of a specific group within the cohorted partition"
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)

openedx/core/djangoapps/course_groups/partition_scheme.py

+"""
+Provides a UserPartition driver for cohorts.
+"""
+import logging
+
+from .cohorts import get_cohort, get_partition_group_id_for_cohort
+
+log = logging.getLogger(__name__)
+
+
+class CohortPartitionScheme(object):
+    """
+    This scheme uses lms cohorts (CourseUserGroups) and cohort-partition
+    mappings (CourseUserGroupPartitionGroup) to map lms users into Partition
+    Groups.
+    """
+
+    @classmethod
+    def get_group_for_user(cls, course_id, user, user_partition, track_function=None):
+        """
+        Returns the Group from the specified user partition to which the user
+        is assigned, via their cohort membership and any mappings from cohorts
+        to partitions / groups that might exist.
+
+        If the user has not yet been assigned to a cohort, an assignment *might*
+        be created on-the-fly, as determined by the course's cohort config.
+        Any such side-effects will be triggered inside the call to
+        cohorts.get_cohort().
+
+        If the user has no cohort mapping, or there is no (valid) cohort ->
+        partition group mapping found, the function returns None.
+        """
+        cohort = get_cohort(user, course_id)
+        if cohort is None:
+            # student doesn't have a cohort
+            return None
+
+        partition_id, group_id = get_partition_group_id_for_cohort(cohort)
+        if partition_id is None:
+            # cohort isn't mapped to any partition group.
+            return None
+
+        if partition_id != user_partition.id:
+            # if we have a match but the partition doesn't match the requested
+            # one it means the mapping is invalid.  the previous state of the
+            # partition configuration may have been modified.
+            log.warn(
+                "partition mismatch in CohortPartitionScheme: %r",
+                {
+                    "requested_partition_id": user_partition.id,
+                    "found_partition_id": partition_id,
+                    "found_group_id": group_id,
+                    "cohort_id": cohort.id,
+                }
+            )
+            # fail silently
+            return None
+
+        group = user_partition.get_group(group_id)
+        if group is None:
+            # if we have a match but the group doesn't exist in the partition,
+            # it means the mapping is invalid.  the previous state of the
+            # partition configuration may have been modified.
+            log.warn(
+                "group not found in CohortPartitionScheme: %r",
+                {
+                    "requested_partition_id": user_partition.id,
+                    "requested_group_id": group_id,
+                    "cohort_id": cohort.id,
+                }
+            )
+            # fail silently
+            return None
+
+        return group

common/djangoapps/course_groups/tests/helpers.py → openedx/core/djangoapps/course_groups/tests/helpers.py

@@ -3,11 +3,12 @@ Helper methods for testing cohorts.
 """
 from factory import post_generation, Sequence
 from factory.django import DjangoModelFactory
-from course_groups.models import CourseUserGroup
 from opaque_keys.edx.locations import SlashSeparatedCourseKey
 from xmodule.modulestore.django import modulestore
 from xmodule.modulestore import ModuleStoreEnum
 
+from ..models import CourseUserGroup
+
 
 class CohortFactory(DjangoModelFactory):
     """

common/djangoapps/course_groups/tests/test_cohorts.py → openedx/core/djangoapps/course_groups/tests/test_cohorts.py

 from django.conf import settings
 from django.contrib.auth.models import User
+from django.db import IntegrityError
 from django.http import Http404
 from django.test import TestCase
 from django.test.utils import override_settings
 from mock import call, patch
-from opaque_keys.edx.locations import SlashSeparatedCourseKey
 
-from course_groups import cohorts
-from course_groups.models import CourseUserGroup
-from course_groups.tests.helpers import topic_name_to_id, config_course_cohorts, CohortFactory
+from opaque_keys.edx.locations import SlashSeparatedCourseKey
 from student.models import CourseEnrollment
 from student.tests.factories import UserFactory
 from xmodule.modulestore.django import modulestore, clear_existing_modulestores
-from xmodule.modulestore.tests.django_utils import TEST_DATA_MIXED_TOY_MODULESTORE
+from xmodule.modulestore.tests.django_utils import TEST_DATA_MIXED_TOY_MODULESTORE, mixed_store_config
 
+from ..models import CourseUserGroup, CourseUserGroupPartitionGroup
+from .. import cohorts
+from ..tests.helpers import topic_name_to_id, config_course_cohorts, CohortFactory
 
 # NOTE: running this with the lms.envs.test config works without
 # manually overriding the modulestore.  However, running with
 # cms.envs.test doesn't.
-@patch("course_groups.cohorts.tracker")
+
+TEST_DATA_DIR = settings.COMMON_TEST_DATA_ROOT
+TEST_MAPPING = {'edX/toy/2012_Fall': 'xml'}
+TEST_DATA_MIXED_MODULESTORE = mixed_store_config(TEST_DATA_DIR, TEST_MAPPING)
+
+
+@patch("openedx.core.djangoapps.course_groups.cohorts.tracker")
 class TestCohortSignals(TestCase):
     def setUp(self):
         self.course_key = SlashSeparatedCourseKey("dummy", "dummy", "dummy")
@@ -446,7 +453,7 @@ class TestCohorts(TestCase):
             lambda: cohorts.get_cohort_by_id(course.id, cohort.id)
         )
 
-    @patch("course_groups.cohorts.tracker")
+    @patch("openedx.core.djangoapps.course_groups.cohorts.tracker")
     def test_add_cohort(self, mock_tracker):
         """
         Make sure cohorts.add_cohort() properly adds a cohort to a course and handles
@@ -469,7 +476,7 @@ class TestCohorts(TestCase):
             lambda: cohorts.add_cohort(SlashSeparatedCourseKey("course", "does_not", "exist"), "My Cohort")
         )
 
-    @patch("course_groups.cohorts.tracker")
+    @patch("openedx.core.djangoapps.course_groups.cohorts.tracker")
     def test_add_user_to_cohort(self, mock_tracker):
         """
         Make sure cohorts.add_user_to_cohort() properly adds a user to a cohort and
@@ -525,3 +532,127 @@ class TestCohorts(TestCase):
             User.DoesNotExist,
             lambda: cohorts.add_user_to_cohort(first_cohort, "non_existent_username")
         )
+
+
+@override_settings(MODULESTORE=TEST_DATA_MIXED_MODULESTORE)
+class TestCohortsAndPartitionGroups(TestCase):
+
+    def setUp(self):
+        """
+        Regenerate a test course and cohorts for each test
+        """
+        self.test_course_key = SlashSeparatedCourseKey("edX", "toy", "2012_Fall")
+        self.course = modulestore().get_course(self.test_course_key)
+
+        self.first_cohort = CohortFactory(course_id=self.course.id, name="FirstCohort")
+        self.second_cohort = CohortFactory(course_id=self.course.id, name="SecondCohort")
+
+        self.partition_id = 1
+        self.group1_id = 10
+        self.group2_id = 20
+
+    def _link_cohort_partition_group(self, cohort, partition_id, group_id):
+        """
+        Utility to create cohort -> partition group assignments in the database.
+        """
+        link = CourseUserGroupPartitionGroup(
+            course_user_group=cohort,
+            partition_id=partition_id,
+            group_id=group_id,
+        )
+        link.save()
+        return link
+
+    def test_get_partition_group_id_for_cohort(self):
+        """
+        Basic test of the partition_group_id accessor function
+        """
+        # api should return nothing for an unmapped cohort
+        self.assertEqual(
+            cohorts.get_partition_group_id_for_cohort(self.first_cohort),
+            (None, None),
+        )
+        # create a link for the cohort in the db
+        link = self._link_cohort_partition_group(
+            self.first_cohort,
+            self.partition_id,
+            self.group1_id
+        )
+        # api should return the specified partition and group
+        self.assertEqual(
+            cohorts.get_partition_group_id_for_cohort(self.first_cohort),
+            (self.partition_id, self.group1_id)
+        )
+        # delete the link in the db
+        link.delete()
+        # api should return nothing again
+        self.assertEqual(
+            cohorts.get_partition_group_id_for_cohort(self.first_cohort),
+            (None, None),
+        )
+
+    def test_multiple_cohorts(self):
+        """
+        Test that multiple cohorts can be linked to the same partition group
+        """
+        self._link_cohort_partition_group(
+            self.first_cohort,
+            self.partition_id,
+            self.group1_id,
+        )
+        self._link_cohort_partition_group(
+            self.second_cohort,
+            self.partition_id,
+            self.group1_id,
+        )
+        self.assertEqual(
+            cohorts.get_partition_group_id_for_cohort(self.first_cohort),
+            (self.partition_id, self.group1_id),
+        )
+        self.assertEqual(
+            cohorts.get_partition_group_id_for_cohort(self.second_cohort),
+            cohorts.get_partition_group_id_for_cohort(self.first_cohort),
+        )
+
+    def test_multiple_partition_groups(self):
+        """
+        Test that a cohort cannot be mapped to more than one partition group
+        """
+        self._link_cohort_partition_group(
+            self.first_cohort,
+            self.partition_id,
+            self.group1_id,
+        )
+        with self.assertRaisesRegexp(IntegrityError, 'not unique'):
+            self._link_cohort_partition_group(
+                self.first_cohort,
+                self.partition_id,
+                self.group2_id,
+            )
+
+    def test_delete_cascade(self):
+        """
+        Test that cohort -> partition group links are automatically deleted
+        when their parent cohort is deleted.
+        """
+        self._link_cohort_partition_group(
+            self.first_cohort,
+            self.partition_id,
+            self.group1_id
+        )
+        self.assertEqual(
+            cohorts.get_partition_group_id_for_cohort(self.first_cohort),
+            (self.partition_id, self.group1_id)
+        )
+        # delete the link
+        self.first_cohort.delete()
+        # api should return nothing at that point
+        self.assertEqual(
+            cohorts.get_partition_group_id_for_cohort(self.first_cohort),
+            (None, None),
+        )
+        # link should no longer exist because of delete cascade
+        with self.assertRaises(CourseUserGroupPartitionGroup.DoesNotExist):
+            CourseUserGroupPartitionGroup.objects.get(
+                course_user_group_id=self.first_cohort.id
+            )

openedx/core/djangoapps/course_groups/tests/test_partition_scheme.py

+"""
+Test the partitions and partitions service
+
+"""
+
+from django.conf import settings
+import django.test
+from django.test.utils import override_settings
+from mock import patch
+
+from student.tests.factories import UserFactory
+from xmodule.partitions.partitions import Group, UserPartition, UserPartitionError
+from xmodule.modulestore.django import modulestore, clear_existing_modulestores
+from xmodule.modulestore.tests.django_utils import mixed_store_config
+from opaque_keys.edx.locations import SlashSeparatedCourseKey
+
+from ..partition_scheme import CohortPartitionScheme
+from ..models import CourseUserGroupPartitionGroup
+from ..cohorts import add_user_to_cohort
+from .helpers import CohortFactory, config_course_cohorts
+
+
+TEST_DATA_DIR = settings.COMMON_TEST_DATA_ROOT
+TEST_MAPPING = {'edX/toy/2012_Fall': 'xml'}
+TEST_DATA_MIXED_MODULESTORE = mixed_store_config(TEST_DATA_DIR, TEST_MAPPING)
+
+
+@override_settings(MODULESTORE=TEST_DATA_MIXED_MODULESTORE)
+class TestCohortPartitionScheme(django.test.TestCase):
+    """
+    Test the logic for linking a user to a partition group based on their cohort.
+    """
+
+    def setUp(self):
+        """
+        Regenerate a course with cohort configuration, partition and groups,
+        and a student for each test.
+        """
+        self.course_key = SlashSeparatedCourseKey("edX", "toy", "2012_Fall")
+        config_course_cohorts(modulestore().get_course(self.course_key), [], cohorted=True)
+
+        self.groups = [Group(10, 'Group 10'), Group(20, 'Group 20')]
+        self.user_partition = UserPartition(
+            0,
+            'Test Partition',
+            'for testing purposes',
+            self.groups,
+            scheme=CohortPartitionScheme
+        )
+        self.student = UserFactory.create()
+
+    def link_cohort_partition_group(self, cohort, partition, group):
+        """
+        Utility for creating cohort -> partition group links
+        """
+        CourseUserGroupPartitionGroup(
+            course_user_group=cohort,
+            partition_id=partition.id,
+            group_id=group.id,
+        ).save()
+
+    def unlink_cohort_partition_group(self, cohort):
+        """
+        Utility for removing cohort -> partition group links
+        """
+        CourseUserGroupPartitionGroup.objects.filter(course_user_group=cohort).delete()
+
+    def assert_student_in_group(self, group, partition=None):
+        """
+        Utility for checking that our test student comes up as assigned to the
+        specified partition (or, if None, no partition at all)
+        """
+        self.assertEqual(
+            CohortPartitionScheme.get_group_for_user(
+                self.course_key,
+                self.student,
+                partition or self.user_partition,
+            ),
+            group
+        )
+
+    def test_student_cohort_assignment(self):
+        """
+        Test that the CohortPartitionScheme continues to return the correct
+        group for a student as the student is moved in and out of different
+        cohorts.
+        """
+        first_cohort, second_cohort = [
+            CohortFactory(course_id=self.course_key) for _ in range(2)
+        ]
+        # place student 0 into first cohort
+        add_user_to_cohort(first_cohort, self.student.username)
+        self.assert_student_in_group(None)
+
+        # link first cohort to group 0 in the partition
+        self.link_cohort_partition_group(
+            first_cohort,
+            self.user_partition,
+            self.groups[0],
+        )
+        # link second cohort to to group 1 in the partition
+        self.link_cohort_partition_group(
+            second_cohort,
+            self.user_partition,
+            self.groups[1],
+        )
+        self.assert_student_in_group(self.groups[0])
+
+        # move student from first cohort to second cohort
+        add_user_to_cohort(second_cohort, self.student.username)
+        self.assert_student_in_group(self.groups[1])
+
+        # move the student out of the cohort
+        second_cohort.users.remove(self.student)
+        self.assert_student_in_group(None)
+
+    def test_cohort_partition_group_assignment(self):
+        """
+        Test that the CohortPartitionScheme returns the correct group for a
+        student in a cohort when the cohort link is created / moved / deleted.
+        """
+        test_cohort = CohortFactory(course_id=self.course_key)
+
+        # assign user to cohort (but cohort isn't linked to a partition group yet)
+        add_user_to_cohort(test_cohort, self.student.username)
+        # scheme should not yet find any link
+        self.assert_student_in_group(None)
+
+        # link cohort to group 0
+        self.link_cohort_partition_group(
+            test_cohort,
+            self.user_partition,
+            self.groups[0],
+        )
+        # now the scheme should find a link
+        self.assert_student_in_group(self.groups[0])
+
+        # link cohort to group 1 (first unlink it from group 0)
+        self.unlink_cohort_partition_group(test_cohort)
+        self.link_cohort_partition_group(
+            test_cohort,
+            self.user_partition,
+            self.groups[1],
+        )
+        # scheme should pick up the link
+        self.assert_student_in_group(self.groups[1])
+
+        # unlink cohort from anywhere
+        self.unlink_cohort_partition_group(
+            test_cohort,
+        )
+        # scheme should now return nothing
+        self.assert_student_in_group(None)
+
+    def setup_student_in_group_0(self):
+        """
+        Utility to set up a cohort, add our student to the cohort, and link
+        the cohort to self.groups[0]
+        """
+        test_cohort = CohortFactory(course_id=self.course_key)
+
+        # link cohort to group 0
+        self.link_cohort_partition_group(
+            test_cohort,
+            self.user_partition,
+            self.groups[0],
+        )
+        # place student into cohort
+        add_user_to_cohort(test_cohort, self.student.username)
+        # check link is correct
+        self.assert_student_in_group(self.groups[0])
+
+    def test_partition_changes_nondestructive(self):
+        """
+        If the name of a user partition is changed, or a group is added to the
+        partition, links from cohorts do not break.
+
+        If the name of a group is changed, links from cohorts do not break.
+        """
+        self.setup_student_in_group_0()
+
+        # to simulate a non-destructive configuration change on the course, create
+        # a new partition with the same id and scheme but with groups renamed and
+        # a group added
+        new_groups = [Group(10, 'New Group 10'), Group(20, 'New Group 20'), Group(30, 'New Group 30')]
+        new_user_partition = UserPartition(
+            0,  # same id
+            'Different Partition',
+            'dummy',
+            new_groups,
+            scheme=CohortPartitionScheme,
+        )
+        # the link should still work
+        self.assert_student_in_group(new_groups[0], new_user_partition)
+
+    def test_missing_group(self):
+        """
+        If the group is deleted (or its id is changed), there's no referential
+        integrity enforced, so any references from cohorts to that group will be
+        lost.  A warning should be logged when links are found from cohorts to
+        groups that no longer exist.
+        """
+        self.setup_student_in_group_0()
+
+        # to simulate a destructive change on the course, create a new partition
+        # with the same id, but different group ids.
+        new_user_partition = UserPartition(
+            0,  # same id
+            'Another Partition',
+            'dummy',
+            [Group(11, 'Not Group 10'), Group(21, 'Not Group 20')],  # different ids
+            scheme=CohortPartitionScheme,
+        )
+        # the partition will be found since it has the same id, but the group
+        # ids aren't present anymore, so the scheme returns None (and logs a
+        # warning)
+        with patch('openedx.core.djangoapps.course_groups.partition_scheme.log') as mock_log:
+            self.assert_student_in_group(None, new_user_partition)
+            self.assertTrue(mock_log.warn.called)
+            self.assertRegexpMatches(mock_log.warn.call_args[0][0], 'group not found')
+
+    def test_missing_partition(self):
+        """
+        If the user partition is deleted (or its id is changed), there's no
+        referential integrity enforced, so any references from cohorts to that
+        partition's groups will be lost.  A warning should be logged when links
+        are found from cohorts to partitions that do not exist.
+        """
+        self.setup_student_in_group_0()
+
+        # to simulate another destructive change on the course, create a new
+        # partition with a different id, but using the same groups.
+        new_user_partition = UserPartition(
+            1,  # different id
+            'Moved Partition',
+            'dummy',
+            [Group(10, 'Group 10'), Group(20, 'Group 20')],  # same ids
+            scheme=CohortPartitionScheme,
+        )
+        # the partition will not be found even though the group ids match, so the
+        # scheme returns None (and logs a warning).
+        with patch('openedx.core.djangoapps.course_groups.partition_scheme.log') as mock_log:
+            self.assert_student_in_group(None, new_user_partition)
+            self.assertTrue(mock_log.warn.called)
+            self.assertRegexpMatches(mock_log.warn.call_args[0][0], 'partition mismatch')
+
+
+class TestExtension(django.test.TestCase):
+    """
+    Ensure that the scheme extension is correctly plugged in (via entry point
+    in setup.py)
+    """
+
+    def test_get_scheme(self):
+        self.assertEqual(UserPartition.get_scheme('cohort'), CohortPartitionScheme)
+        with self.assertRaisesRegexp(UserPartitionError, 'Unrecognized scheme'):
+            UserPartition.get_scheme('other')

common/djangoapps/course_groups/tests/test_views.py → openedx/core/djangoapps/course_groups/tests/test_views.py

@@ -4,25 +4,23 @@ Tests for course group views
 from collections import namedtuple
 import json
 
+from collections import namedtuple
 from django.contrib.auth.models import User
 from django.http import Http404
 from django.test.client import RequestFactory
 from django.test.utils import override_settings
-from opaque_keys.edx.locations import SlashSeparatedCourseKey
 
-from course_groups.cohorts import (
-    get_cohort, CohortAssignmentType, get_cohort_by_name, DEFAULT_COHORT_NAME
-)
-from course_groups.models import CourseUserGroup
-from course_groups.tests.helpers import config_course_cohorts, CohortFactory
-from course_groups.views import (
-    list_cohorts, add_cohort, users_in_cohort, add_users_to_cohort, remove_user_from_cohort
-)
 from xmodule.modulestore.tests.django_utils import TEST_DATA_MOCK_MODULESTORE
 from student.models import CourseEnrollment
 from student.tests.factories import UserFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory
+from opaque_keys.edx.locations import SlashSeparatedCourseKey
+
+from ..models import CourseUserGroup
+from ..views import list_cohorts, add_cohort, users_in_cohort, add_users_to_cohort, remove_user_from_cohort
+from ..cohorts import get_cohort, CohortAssignmentType, get_cohort_by_name, DEFAULT_COHORT_NAME
+from .helpers import config_course_cohorts, CohortFactory
 
 
 @override_settings(MODULESTORE=TEST_DATA_MOCK_MODULESTORE)

common/djangoapps/user_api/api/account.py → openedx/core/djangoapps/user_api/api/account.py

@@ -11,8 +11,8 @@ from django.db import transaction, IntegrityError
 from django.core.validators import validate_email, validate_slug, ValidationError
 from django.contrib.auth.forms import PasswordResetForm
 
-from user_api.models import User, UserProfile, Registration, PendingEmailChange
-from user_api.helpers import intercept_errors
+from ..models import User, UserProfile, Registration, PendingEmailChange
+from ..helpers import intercept_errors
 
 
 USERNAME_MIN_LENGTH = 2

common/djangoapps/user_api/api/course_tag.py → openedx/core/djangoapps/user_api/api/course_tag.py

@@ -7,7 +7,7 @@ Stores global metadata using the UserPreference model, and per-course metadata u
 UserCourseTag model.
 """
 
-from user_api.models import UserCourseTag
+from ..models import UserCourseTag
 
 # Scopes
 # (currently only allows per-course tags.  Can be expanded to support

common/djangoapps/user_api/api/profile.py → openedx/core/djangoapps/user_api/api/profile.py

@@ -13,9 +13,9 @@ from django.db import IntegrityError
 from pytz import UTC
 import analytics
 
-from user_api.models import User, UserProfile, UserPreference, UserOrgTag
-from user_api.helpers import intercept_errors
 from eventtracking import tracker
+from ..models import User, UserProfile, UserPreference, UserOrgTag
+from ..helpers import intercept_errors
 
 log = logging.getLogger(__name__)
 
@@ -34,6 +34,7 @@ class ProfileInvalidField(ProfileRequestError):
     """ The proposed value for a field is not in a valid format. """
 
     def __init__(self, field, value):
+        super(ProfileInvalidField, self).__init__()
         self.field = field
         self.value = value
 

common/djangoapps/user_api/helpers.py → openedx/core/djangoapps/user_api/helpers.py

@@ -12,7 +12,7 @@ from django.http import HttpResponseBadRequest
 LOGGER = logging.getLogger(__name__)
 
 
-def intercept_errors(api_error, ignore_errors=[]):
+def intercept_errors(api_error, ignore_errors=None):
     """
     Function decorator that intercepts exceptions
     and translates them into API-specific errors (usually an "internal" error).
@@ -33,13 +33,20 @@ def intercept_errors(api_error, ignore_errors=[]):
 
     """
     def _decorator(func):
+        """
+        Function decorator that intercepts exceptions and translates them into API-specific errors.
+        """
         @wraps(func)
         def _wrapped(*args, **kwargs):
+            """
+            Wrapper that evaluates a function, intercepting exceptions and translating them into
+            API-specific errors.
+            """
             try:
                 return func(*args, **kwargs)
             except Exception as ex:
                 # Raise the original exception if it's in our list of "ignored" errors
-                for ignored in ignore_errors:
+                for ignored in ignore_errors or []:
                     if isinstance(ex, ignored):
                         raise
 

common/djangoapps/user_api/management/tests/test_email_opt_in_list.py → openedx/core/djangoapps/user_api/management/tests/test_email_opt_in_list.py

@@ -19,9 +19,9 @@ from xmodule.modulestore.tests.factories import CourseFactory
 from student.tests.factories import UserFactory, CourseEnrollmentFactory
 from student.models import CourseEnrollment
 
-import user_api.api.profile as profile_api
-from user_api.models import UserOrgTag
-from user_api.management.commands import email_opt_in_list
+import openedx.core.djangoapps.user_api.api.profile as profile_api
+from openedx.core.djangoapps.user_api.models import UserOrgTag
+from openedx.core.djangoapps.user_api.management.commands import email_opt_in_list
 
 
 MODULESTORE_CONFIG = mixed_store_config(settings.COMMON_TEST_DATA_ROOT, {}, include_xml=False)

common/djangoapps/user_api/middleware.py → openedx/core/djangoapps/user_api/middleware.py

@@ -8,7 +8,8 @@ from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey
 
 from track.contexts import COURSE_REGEX
-from user_api.models import UserCourseTag
+
+from .models import UserCourseTag
 
 
 class UserTagsEventContextMiddleware(object):

openedx/core/djangoapps/user_api/partition_schemes.py

+"""
+Provides partition support to the user service.
+"""
+
+import random
+import api.course_tag as course_tag_api
+
+from xmodule.partitions.partitions import UserPartitionError
+
+
+class RandomUserPartitionScheme(object):
+    """
+    This scheme randomly assigns users into the partition's groups.
+    """
+    RANDOM = random.Random()
+
+    @classmethod
+    def get_group_for_user(cls, course_id, user, user_partition, track_function=None):
+        """
+        Returns the group from the specified user position to which the user is assigned.
+        If the user has not yet been assigned, a group will be randomly chosen for them.
+        """
+        partition_key = cls._key_for_partition(user_partition)
+        group_id = course_tag_api.get_course_tag(user, course_id, partition_key)
+        group = user_partition.get_group(int(group_id)) if not group_id is None else None
+        if group is None:
+            if not user_partition.groups:
+                raise UserPartitionError('Cannot assign user to an empty user partition')
+
+            # pylint: disable=fixme
+            # TODO: had a discussion in arch council about making randomization more
+            # deterministic (e.g. some hash).  Could do that, but need to be careful not
+            # to introduce correlation between users or bias in generation.
+            group = cls.RANDOM.choice(user_partition.groups)
+
+            # persist the value as a course tag
+            course_tag_api.set_course_tag(user, course_id, partition_key, group.id)
+
+            if track_function:
+                # emit event for analytics
+                # FYI - context is always user ID that is logged in, NOT the user id that is
+                # being operated on. If instructor can move user explicitly, then we should
+                # put in event_info the user id that is being operated on.
+                event_info = {
+                    'group_id': group.id,
+                    'group_name': group.name,
+                    'partition_id': user_partition.id,
+                    'partition_name': user_partition.name
+                }
+                # pylint: disable=fixme
+                # TODO: Use the XBlock publish api instead
+                track_function('xmodule.partitions.assigned_user_to_partition', event_info)
+
+        return group
+
+    @classmethod
+    def _key_for_partition(cls, user_partition):
+        """
+        Returns the key to use to look up and save the user's group for a given user partition.
+        """
+        return 'xblock.partition_service.partition_{0}'.format(user_partition.id)