diff --git a/autograder/rest_api/tests/test_views/test_group_views/test_group_views.py b/autograder/rest_api/tests/test_views/test_group_views/test_group_views.py
index caa19d1b..b8a7ca56 100644
--- a/autograder/rest_api/tests/test_views/test_group_views/test_group_views.py
+++ b/autograder/rest_api/tests/test_views/test_group_views/test_group_views.py
@@ -428,7 +428,7 @@ def group_url(self, group: ag_models.Group) -> str:
         return reverse('group-detail', kwargs={'pk': group.pk})
 
 
-class UpdateGroupTestCase(AGViewTestBase):
+class UpdateGroupExtendedDueDatesTestCase(AGViewTestBase):
     def setUp(self):
         super().setUp()
         self.new_due_date = timezone.now()
@@ -438,49 +438,6 @@ def setUp(self):
         self.course = self.project.course
         self.admin = obj_build.make_admin_user(self.course)
 
-    def get_names(self, users):
-        return list(sorted((user.username for user in users)))
-
-    def test_admin_update_admin_and_staff_group_members(self):
-        group = obj_build.make_group(
-            num_members=2, members_role=obj_build.UserRole.staff, project=self.project)
-        new_members = list(group.members.all())[:-1] + [obj_build.make_admin_user(self.course)]
-        response = self.do_patch_object_test(
-            group, self.client, self.admin, self.group_url(group),
-            {'member_names': self.get_names(new_members)},
-            ignore_fields=['members'])
-
-        self.assertGreater(len(new_members), self.project.max_group_size)
-        self.assertCountEqual(
-            [serialize_user(user) for user in new_members], response.data['members'])
-
-    def test_admin_update_student_group_members(self):
-        group = obj_build.make_group(
-            num_members=2, members_role=obj_build.UserRole.student, project=self.project)
-        new_members = list(group.members.all())[:-1] + [obj_build.make_student_user(self.course)]
-        response = self.do_patch_object_test(
-            group, self.client, self.admin, self.group_url(group),
-            {'member_names': self.get_names(new_members)},
-            ignore_fields=['members'])
-
-        self.assertGreater(len(new_members), self.project.max_group_size)
-        self.assertCountEqual(
-            [serialize_user(user) for user in new_members], response.data['members'])
-
-    def test_admin_update_guest_group_members(self):
-        self.project.validate_and_update(guests_can_submit=True)
-        group = obj_build.make_group(
-            num_members=2, members_role=obj_build.UserRole.guest, project=self.project)
-        new_members = list(group.members.all())[:-1] + [obj_build.make_user()]
-        response = self.do_patch_object_test(
-            group, self.client, self.admin, self.group_url(group),
-            {'member_names': self.get_names(new_members)},
-            ignore_fields=['members'])
-
-        self.assertGreater(len(new_members), self.project.max_group_size)
-        self.assertCountEqual(
-            [serialize_user(user) for user in new_members], response.data['members'])
-
     def test_admin_update_group_deprecated_extended_due_date(self):
         group = obj_build.make_group(project=self.project)
 
@@ -506,6 +463,31 @@ def test_admin_update_group_deprecated_extended_due_date(self):
             group, self.client, self.admin, self.group_url(group),
             {'extended_due_date': None})
 
+    def test_admin_update_deprecated_extended_due_date_mixed_use(self):
+        group = obj_build.make_group(project=self.project)
+
+        self.do_patch_object_invalid_args_test(
+            group, self.client, self.admin, self.group_url(group),
+            {
+                'extended_due_date': self.new_due_date,
+                'soft_extended_due_date': self.new_due_date
+            })
+
+        self.do_patch_object_invalid_args_test(
+            group, self.client, self.admin, self.group_url(group),
+            {
+                'extended_due_date': self.new_due_date,
+                'hard_extended_due_date': self.new_due_date
+            })
+
+        self.do_patch_object_invalid_args_test(
+            group, self.client, self.admin, self.group_url(group),
+            {
+                'extended_due_date': self.new_due_date,
+                'soft_extended_due_date': self.new_due_date,
+                'hard_extended_due_date': self.new_due_date
+            })
+
     def test_admin_update_soft_extended_due_date(self):
         group = obj_build.make_group(
             project=self.project, hard_extended_due_date=self.new_due_date)
@@ -527,6 +509,7 @@ def test_admin_update_soft_extended_due_date(self):
         self.do_patch_object_test(
             group, self.client, self.admin, self.group_url(group),
             {
+                'hard_extended_due_date': group.hard_extended_due_date,
                 'soft_extended_due_date': valid_soft_extended_due_date,
                 'extended_due_date': group.extended_due_date
             },
@@ -561,6 +544,7 @@ def test_admin_update_hard_extended_due_date(self):
             group, self.client, self.admin, self.group_url(group),
             {
                 'hard_extended_due_date': valid_hard_extended_due_date,
+                'soft_extended_due_date': group.soft_extended_due_date,
                 'extended_due_date': group.extended_due_date
             },
             expected_response_overrides={
@@ -571,6 +555,91 @@ def test_admin_update_hard_extended_due_date(self):
                     second=0, microsecond=0)
             })
 
+    def test_admin_update_soft_and_hard_extended_deadlines(self):
+        group = obj_build.make_group(project=self.project)
+        later = self.new_due_date + datetime.timedelta(days=1)
+        response = self.do_patch_object_invalid_args_test(
+            group, self.client, self.admin, self.group_url(group),
+            {
+                'hard_extended_due_date': self.new_due_date,
+                'soft_extended_due_date': later,
+                'extended_due_date': group.extended_due_date
+            })
+        self.assertIn('hard_extended_due_date', response.data)
+
+        self.do_patch_object_test(
+            group, self.client, self.admin, self.group_url(group),
+            {
+                'soft_extended_due_date': self.new_due_date,
+                'hard_extended_due_date': later,
+                'extended_due_date': group.extended_due_date
+            },
+            expected_response_overrides={
+                'soft_extended_due_date': self.new_due_date.replace(second=0, microsecond=0),
+                'hard_extended_due_date': later.replace(second=0, microsecond=0),
+                'extended_due_date': self.new_due_date.replace(second=0, microsecond=0)
+
+            })
+
+
+    def group_url(self, group: ag_models.Group) -> str:
+        return reverse('group-detail', kwargs={'pk': group.pk})
+
+
+class UpdateGroupTestCase(AGViewTestBase):
+    def setUp(self):
+        super().setUp()
+        self.new_due_date = timezone.now()
+
+        self.client = APIClient()
+        self.project = obj_build.make_project()
+        self.course = self.project.course
+        self.admin = obj_build.make_admin_user(self.course)
+
+    def get_names(self, users):
+        return list(sorted((user.username for user in users)))
+
+    def test_admin_update_admin_and_staff_group_members(self):
+        group = obj_build.make_group(
+            num_members=2, members_role=obj_build.UserRole.staff, project=self.project)
+        new_members = list(group.members.all())[:-1] + [obj_build.make_admin_user(self.course)]
+        response = self.do_patch_object_test(
+            group, self.client, self.admin, self.group_url(group),
+            {'member_names': self.get_names(new_members)},
+            ignore_fields=['members'])
+
+        self.assertGreater(len(new_members), self.project.max_group_size)
+        self.assertCountEqual(
+            [serialize_user(user) for user in new_members], response.data['members'])
+
+    def test_admin_update_student_group_members(self):
+        group = obj_build.make_group(
+            num_members=2, members_role=obj_build.UserRole.student, project=self.project)
+        new_members = list(group.members.all())[:-1] + [obj_build.make_student_user(self.course)]
+        response = self.do_patch_object_test(
+            group, self.client, self.admin, self.group_url(group),
+            {'member_names': self.get_names(new_members)},
+            ignore_fields=['members'])
+
+        self.assertGreater(len(new_members), self.project.max_group_size)
+        self.assertCountEqual(
+            [serialize_user(user) for user in new_members], response.data['members'])
+
+    def test_admin_update_guest_group_members(self):
+        self.project.validate_and_update(guests_can_submit=True)
+        group = obj_build.make_group(
+            num_members=2, members_role=obj_build.UserRole.guest, project=self.project)
+        new_members = list(group.members.all())[:-1] + [obj_build.make_user()]
+        response = self.do_patch_object_test(
+            group, self.client, self.admin, self.group_url(group),
+            {'member_names': self.get_names(new_members)},
+            ignore_fields=['members'])
+
+        self.assertGreater(len(new_members), self.project.max_group_size)
+        self.assertCountEqual(
+            [serialize_user(user) for user in new_members], response.data['members'])
+
+
     def test_admin_update_group_invalid_members(self):
         group = obj_build.make_group(project=self.project)
         new_members = self.get_names(list(group.members.all())[:-1]) + ['stove']
@@ -804,66 +873,3 @@ def test_non_admin_delete_group_permission_denied(self) -> None:
 
         self.group = ag_models.Group.objects.get(pk=self.group.pk)
         self.assertEqual(original_member_names, self.group.member_names)
-
-
-class CleanExtendedDueDatesTests(UnitTestBase):
-    def setUp(self):
-        super().setUp()
-        self.group = obj_build.make_group()
-        self.new_time = '2020-09-12 17:52:05.538324Z'
-
-    def test_mixed_use_deprecated_extended_due_date(self) -> None:
-        update_data = {
-            'extended_due_date': self.new_time,
-            'soft_extended_due_date': self.new_time,
-            'foo': 'bar'
-        }
-        with self.assertRaises(exceptions.ValidationError) as cm:
-            _ = clean_extended_due_dates(update_data, self.group)
-        self.assertIn('extended_due_date', cm.exception.detail)
-
-        update_data = {'extended_due_date': self.new_time, 'hard_extended_due_date': self.new_time}
-        with self.assertRaises(exceptions.ValidationError) as cm:
-            _ = clean_extended_due_dates(update_data, self.group)
-        self.assertIn('extended_due_date', cm.exception.detail)
-
-    def test_updated_deprecated_extended_due_date(self) -> None:
-        update_data = {
-            'extended_due_date': self.new_time,
-            'soft_extended_due_date': self.group.soft_extended_due_date,
-            'hard_extended_due_date': self.group.hard_extended_due_date,
-            'foo': 'bar'
-        }
-        new_update_data = clean_extended_due_dates(update_data, self.group)
-        expected_new_update_data = {'extended_due_date': self.new_time, 'foo': 'bar'}
-        self.assertEqual(new_update_data, expected_new_update_data)
-
-    def test_updated_soft_extended_due_date(self) -> None:
-        update_data = {
-            'extended_due_date': self.group.extended_due_date,
-            'soft_extended_due_date': self.new_time,
-            'hard_extended_due_date': self.group.hard_extended_due_date,
-            'foo': 'bar'
-        }
-        new_update_data = clean_extended_due_dates(update_data, self.group)
-        expected_new_update_data = {
-            'soft_extended_due_date': self.new_time,
-            'hard_extended_due_date': self.group.hard_extended_due_date,
-            'foo': 'bar'
-        }
-        self.assertEqual(new_update_data, expected_new_update_data)
-
-    def test_updated_hard_extended_due_date(self) -> None:
-        update_data = {
-            'extended_due_date': self.group.extended_due_date,
-            'soft_extended_due_date': self.group.soft_extended_due_date,
-            'hard_extended_due_date': self.new_time,
-            'foo': 'bar'
-        }
-        new_update_data = clean_extended_due_dates(update_data, self.group)
-        expected_new_update_data = {
-            'soft_extended_due_date': self.group.soft_extended_due_date,
-            'hard_extended_due_date': self.new_time,
-            'foo': 'bar'
-        }
-        self.assertEqual(new_update_data, expected_new_update_data)