Remove dead code

common/djangoapps/course_groups/cohorts.py

@@ -277,13 +277,6 @@ def add_cohort(course_key, name):
     )
 
 
-class CohortConflict(Exception):
-    """
-    Raised when user to be added is already in another cohort in same course.
-    """
-    pass
-
-
 def add_user_to_cohort(cohort, username_or_email):
     """
     Look up the given user, and if successful, add them to the specified cohort.

common/djangoapps/course_groups/tests/test_cohorts.py

@@ -408,34 +408,3 @@ class TestCohorts(django.test.TestCase):
             User.DoesNotExist,
             lambda: cohorts.add_user_to_cohort(first_cohort, "non_existent_username")
         )
-
-    def test_delete_empty_cohort(self):
-        """
-        Make sure that cohorts.delete_empty_cohort() properly removes an empty cohort
-        for a given course.
-        """
-        course = modulestore().get_course(self.toy_course_key)
-        user = UserFactory(username="Username", email="a@b.com")
-        empty_cohort = CohortFactory(course_id=course.id, name="EmptyCohort")
-        nonempty_cohort = CohortFactory(course_id=course.id, name="NonemptyCohort")
-        nonempty_cohort.users.add(user)
-
-        cohorts.delete_empty_cohort(course.id, "EmptyCohort")
-
-        # Make sure we cannot access the deleted cohort
-        self.assertRaises(
-            CourseUserGroup.DoesNotExist,
-            lambda: cohorts.get_cohort_by_id(course.id, empty_cohort.id)
-        )
-        self.assertRaises(
-            ValueError,
-            lambda: cohorts.delete_empty_cohort(course.id, "NonemptyCohort")
-        )
-        self.assertRaises(
-            CourseUserGroup.DoesNotExist,
-            lambda: cohorts.delete_empty_cohort(SlashSeparatedCourseKey('course', 'does_not', 'exist'), "EmptyCohort")
-        )
-        self.assertRaises(
-            CourseUserGroup.DoesNotExist,
-            lambda: cohorts.delete_empty_cohort(course.id, "NonExistentCohort")
-        )