Merge pull request #20936 from cpennington/discount-holdback

Discount holdback

lms/djangoapps/experiments/stable_bucketing.py

+"""
+An implementation of a stable bucketing algorithm that can be used
+to reliably group users into experiments.
+"""
+
+import hashlib
+import re
+
+
+def stable_bucketing_hash_group(group_name, group_count, username):
+    """
+    Return the bucket that a user should be in for a given stable bucketing assignment.
+
+    This function has been verified to return the same values as the stable bucketing
+    functions in javascript and the master experiments table.
+
+    Arguments:
+        group_name: The name of the grouping/experiment.
+        group_count: How many groups to bucket users into.
+        username: The username of the user being bucketed.
+    """
+    hasher = hashlib.md5()
+    hasher.update(group_name.encode('utf-8'))
+    hasher.update(username.encode('utf-8'))
+    hash_str = hasher.hexdigest()
+
+    return int(re.sub('[8-9a-f]', '1', re.sub('[0-7]', '0', hash_str)), 2) % group_count

lms/djangoapps/experiments/utils.py

@@ -4,9 +4,7 @@ Utilities to facilitate experimentation
 
 from __future__ import absolute_import
 
-import hashlib
 import logging
-import re
 from decimal import Decimal
 
 import six
@@ -27,6 +25,9 @@ from openedx.features.course_duration_limits.models import CourseDurationLimitCo
 from student.models import CourseEnrollment
 from xmodule.partitions.partitions_service import get_all_partitions_for_course, get_user_partition_groups
 
+# Import this for backwards compatibility (so that anyone importing this function from here doesn't break)
+from .stable_bucketing import stable_bucketing_hash_group  # pylint: disable=unused-import
+
 logger = logging.getLogger(__name__)
 
 
@@ -386,23 +387,3 @@ def get_program_context(course, user_enrollments):
             }
     return program_key
 # TODO: clean up as part of REVEM-199 (START)
-
-
-def stable_bucketing_hash_group(group_name, group_count, username):
-    """
-    Return the bucket that a user should be in for a given stable bucketing assignment.
-
-    This function has been verified to return the same values as the stable bucketing
-    functions in javascript and the master experiments table.
-
-    Arguments:
-        group_name: The name of the grouping/experiment.
-        group_count: How many groups to bucket users into.
-        username: The username of the user being bucketed.
-    """
-    hasher = hashlib.md5()
-    hasher.update(group_name.encode('utf-8'))
-    hasher.update(username.encode('utf-8'))
-    hash_str = hasher.hexdigest()
-
-    return int(re.sub('[8-9a-f]', '1', re.sub('[0-7]', '0', hash_str)), 2) % group_count

openedx/features/course_duration_limits/resolvers.py

@@ -15,7 +15,7 @@ from eventtracking import tracker
 
 from course_modes.models import CourseMode
 from courseware.date_summary import verified_upgrade_deadline_link
-from lms.djangoapps.experiments.utils import stable_bucketing_hash_group
+from lms.djangoapps.experiments.stable_bucketing import stable_bucketing_hash_group
 from openedx.core.djangoapps.catalog.utils import get_course_run_details
 from openedx.core.djangoapps.schedules.resolvers import (
     BinnedSchedulesBaseResolver,

openedx/features/discounts/applicability.py

@@ -8,11 +8,18 @@ Keep in mind that the code in this file only applies to discounts controlled in
 not other discounts like coupons or enterprise/program offers configured in ecommerce.
 
 """
+from datetime import datetime
+
+import crum
+import pytz
+
 from course_modes.models import CourseMode
 from entitlements.models import CourseEntitlement
+from lms.djangoapps.experiments.stable_bucketing import stable_bucketing_hash_group
 from openedx.core.djangoapps.waffle_utils import WaffleFlag, WaffleFlagNamespace
 from openedx.features.discounts.models import DiscountRestrictionConfig
 from student.models import CourseEnrollment
+from track import segment
 
 # .. feature_toggle_name: discounts.enable_discounting
 # .. feature_toggle_type: flag
@@ -31,6 +38,8 @@ DISCOUNT_APPLICABILITY_FLAG = WaffleFlag(
     flag_undefined_default=False
 )
 
+DISCOUNT_APPLICABILITY_HOLDBACK = 'first_purchase_discount_holdback'
+
 
 def can_receive_discount(user, course):  # pylint: disable=unused-argument
     """
@@ -66,9 +75,48 @@ def can_receive_discount(user, course):  # pylint: disable=unused-argument
     if CourseEntitlement.objects.filter(user=user).exists():
         return False
 
+    # Excute holdback
+    if _is_in_holdback(user):
+        return False
+
     return True
 
 
+def _is_in_holdback(user):
+    """
+    Return whether the specified user is in the first-purchase-discount holdback group.
+    """
+    if datetime(2020, 8, 1, tzinfo=pytz.UTC) <= datetime.now(tz=pytz.UTC):
+        return False
+
+    if not datetime(2019, 8, 1, tzinfo=pytz.UTC) <= user.date_joined <= datetime(2019, 11, 1, tzinfo=pytz.UTC):
+        return False
+
+    # Holdback is 50/50
+    bucket = stable_bucketing_hash_group(DISCOUNT_APPLICABILITY_HOLDBACK, 2, user.username)
+
+    request = crum.get_current_request()
+    if hasattr(request, 'session') and DISCOUNT_APPLICABILITY_HOLDBACK not in request.session:
+
+        properties = {
+            'site': request.site.domain,
+            'app_label': 'discounts',
+            'nonInteraction': 1,
+            'bucket': bucket,
+            'experiment': 'REVEM-363',
+        }
+        segment.track(
+            user_id=user.id,
+            event_name='edx.bi.experiment.user.bucketed',
+            properties=properties,
+        )
+
+        # Mark that we've recorded this bucketing, so that we don't do it again this session
+        request.session[DISCOUNT_APPLICABILITY_HOLDBACK] = True
+
+    return bucket == 0
+
+
 def discount_percentage():
     """
     Get the configured discount amount.

openedx/features/discounts/tests/test_applicability.py

 """Tests of openedx.features.discounts.applicability"""
 # -*- coding: utf-8 -*-
 
-from datetime import timedelta
+from datetime import timedelta, datetime
 import ddt
 from django.utils.timezone import now
+from mock import patch, Mock
+import pytz
 
 from course_modes.models import CourseMode
 from course_modes.tests.factories import CourseModeFactory
@@ -15,7 +17,7 @@ from student.tests.factories import UserFactory, CourseEnrollmentFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory
 
-from ..applicability import can_receive_discount, DISCOUNT_APPLICABILITY_FLAG
+from ..applicability import can_receive_discount, DISCOUNT_APPLICABILITY_FLAG, _is_in_holdback
 
 
 @ddt.ddt
@@ -31,6 +33,10 @@ class TestApplicability(ModuleStoreTestCase):
         self.course = CourseFactory.create(run='test', display_name='test')
         CourseModeFactory.create(course_id=self.course.id, mode_slug='verified')
 
+        holdback_patcher = patch('openedx.features.discounts.applicability._is_in_holdback', return_value=False)
+        self.mock_holdback = holdback_patcher.start()
+        self.addCleanup(holdback_patcher.stop)
+
     def test_can_receive_discount(self):
         # Right now, no one should be able to receive the discount
         applicability = can_receive_discount(user=self.user, course=self.course)
@@ -95,3 +101,44 @@ class TestApplicability(ModuleStoreTestCase):
 
         applicability = can_receive_discount(user=self.user, course=self.course)
         assert applicability == (entitlement_mode is None)
+
+    @override_waffle_flag(DISCOUNT_APPLICABILITY_FLAG, active=True)
+    def test_holdback_denies_discount(self):
+        """
+        Ensure that users in the holdback do not receive the discount.
+        """
+        self.mock_holdback.return_value = True
+
+        applicability = can_receive_discount(user=self.user, course=self.course)
+        assert not applicability
+
+    @ddt.data(
+        (0, True),
+        (1, False),
+    )
+    @ddt.unpack
+    def test_holdback_group_ids(self, group_number, in_holdback):
+        with patch('openedx.features.discounts.applicability.stable_bucketing_hash_group', return_value=group_number):
+            with patch.object(self.user, 'date_joined', datetime(2019, 8, 1, 0, 1, tzinfo=pytz.UTC)):
+                assert _is_in_holdback(self.user) == in_holdback
+
+    @ddt.data(
+        (datetime(2019, 7, 31, tzinfo=pytz.UTC), False),
+        (datetime(2019, 8, 1, 0, 1, tzinfo=pytz.UTC), True),
+        (datetime(2019, 10, 30, 23, 59, tzinfo=pytz.UTC), True),
+        (datetime(2019, 11, 1, 0, 1, tzinfo=pytz.UTC), False),
+    )
+    @ddt.unpack
+    def test_holdback_registration_limits(self, registration_date, in_holdback):
+        with patch('openedx.features.discounts.applicability.stable_bucketing_hash_group', return_value=0):
+            with patch.object(self.user, 'date_joined', registration_date):
+                assert _is_in_holdback(self.user) == in_holdback
+
+    def test_holdback_expiry(self):
+        with patch('openedx.features.discounts.applicability.stable_bucketing_hash_group', return_value=0):
+            with patch.object(self.user, 'date_joined', datetime(2019, 8, 1, 0, 1, tzinfo=pytz.UTC)):
+                with patch(
+                    'openedx.features.discounts.applicability.datetime',
+                    Mock(now=Mock(return_value=datetime(2020, 8, 1, 0, 1, tzinfo=pytz.UTC)))
+                ):
+                    assert not _is_in_holdback(self.user)