From 65f8731a73d66023c1e058663eb273a9533474f7 Mon Sep 17 00:00:00 2001
From: Nimisha Asthagiri <nasthagiri@edx.org>
Date: Mon, 11 Sep 2017 14:32:19 -0400
Subject: [PATCH] Update schedule start only if new course start date is in the
 future

---
 openedx/core/djangoapps/schedules/signals.py  |  6 ++-
 .../schedules/tests/test_signals.py           | 39 +++++++++++++------
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/openedx/core/djangoapps/schedules/signals.py b/openedx/core/djangoapps/schedules/signals.py
index 1b6e4320b8..2a8f01c44f 100644
--- a/openedx/core/djangoapps/schedules/signals.py
+++ b/openedx/core/djangoapps/schedules/signals.py
@@ -69,9 +69,11 @@ def create_schedule(sender, **kwargs):
 @receiver(COURSE_START_DATE_CHANGED, dispatch_uid="update_schedules_on_course_start_changed")
 def update_schedules_on_course_start_changed(sender, updated_course_overview, previous_start_date, **kwargs):
     """
-    Updates all course schedules if course hasn't started yet.
+    Updates all course schedules if course hasn't started yet and
+    the updated start date is still in the future.
     """
-    if previous_start_date > timezone.now():
+    current_time = timezone.now()
+    if previous_start_date > current_time and updated_course_overview.start > current_time:
         upgrade_deadline = _calculate_upgrade_deadline(
             updated_course_overview.id,
             content_availability_date=updated_course_overview.start,
diff --git a/openedx/core/djangoapps/schedules/tests/test_signals.py b/openedx/core/djangoapps/schedules/tests/test_signals.py
index 11c5454cc0..3d5c550b11 100644
--- a/openedx/core/djangoapps/schedules/tests/test_signals.py
+++ b/openedx/core/djangoapps/schedules/tests/test_signals.py
@@ -1,4 +1,7 @@
+from collections import namedtuple
 import datetime
+import ddt
+from enum import Enum
 from mock import patch
 from pytz import utc
 
@@ -78,7 +81,9 @@ class CreateScheduleTests(SharedModuleStoreTestCase):
             enrollment.schedule
 
 
+@ddt.ddt
 @skip_unless_lms
+@patch('openedx.core.djangoapps.schedules.signals.get_current_site')
 class UpdateScheduleTests(SharedModuleStoreTestCase):
     ENABLED_SIGNALS = ['course_published']
     VERIFICATION_DEADLINE_DAYS = 14
@@ -96,30 +101,42 @@ class UpdateScheduleTests(SharedModuleStoreTestCase):
             _strip_secs(expected_start) + datetime.timedelta(days=self.VERIFICATION_DEADLINE_DAYS),
         )
 
-    @patch('openedx.core.djangoapps.schedules.signals.get_current_site')
-    def test_schedule_updated(self, mock_get_current_site):
+    def test_updated_since_course_not_started(self, mock_get_current_site):
         mock_get_current_site.return_value = self.site
 
-        course = _create_course_run(self_paced=True, start_day_offset=5)
+        course = _create_course_run(self_paced=True, start_day_offset=5)  # course starts in future
         enrollment = CourseEnrollmentFactory(course_id=course.id, mode=CourseMode.AUDIT)
-
         self.assert_schedule_dates(enrollment.schedule, enrollment.course_overview.start)
-        course.start = course.start + datetime.timedelta(days=3)
+
+        course.start = course.start + datetime.timedelta(days=3)  # new course start changes to another future date
         self.store.update_item(course, ModuleStoreEnum.UserID.test)
         enrollment = CourseEnrollment.objects.get(id=enrollment.id)
-        self.assert_schedule_dates(enrollment.schedule, course.start)
+        self.assert_schedule_dates(enrollment.schedule, course.start)  # start set to new course start
 
-    @patch('openedx.core.djangoapps.schedules.signals.get_current_site')
-    def test_schedule_not_updated(self, mock_get_current_site):
+    def test_not_updated_since_course_already_started(self, mock_get_current_site):
         mock_get_current_site.return_value = self.site
 
-        course = _create_course_run(self_paced=True, start_day_offset=-5)
+        course = _create_course_run(self_paced=True, start_day_offset=-5)  # course starts in past
         enrollment = CourseEnrollmentFactory(course_id=course.id, mode=CourseMode.AUDIT)
         self.assert_schedule_dates(enrollment.schedule, enrollment.created)
 
-        course.start = course.start + datetime.timedelta(days=3)
+        course.start = course.start + datetime.timedelta(days=3)  # new course start changes to another future date
         self.store.update_item(course, ModuleStoreEnum.UserID.test)
-        self.assert_schedule_dates(enrollment.schedule, enrollment.created)
+        enrollment = CourseEnrollment.objects.get(id=enrollment.id)
+        self.assert_schedule_dates(enrollment.schedule, enrollment.created)  # start remains unchanged
+
+    def test_not_updated_since_new_start_in_past(self, mock_get_current_site):
+        mock_get_current_site.return_value = self.site
+
+        course = _create_course_run(self_paced=True, start_day_offset=5)  # course starts in future
+        enrollment = CourseEnrollmentFactory(course_id=course.id, mode=CourseMode.AUDIT)
+        previous_start = enrollment.course_overview.start
+        self.assert_schedule_dates(enrollment.schedule, previous_start)
+
+        course.start = course.start + datetime.timedelta(days=-10)  # new course start changes to a past date
+        self.store.update_item(course, ModuleStoreEnum.UserID.test)
+        enrollment = CourseEnrollment.objects.get(id=enrollment.id)
+        self.assert_schedule_dates(enrollment.schedule, previous_start)  # start remains unchanged
 
 
 def _create_course_run(self_paced=True, start_day_offset=-1):