Test case for django ticket #21281. https://code.djangoproject.com/ticket/21281

testcase.diff

diff --git a/tests/test_utils/tests.py b/tests/test_utils/tests.py
index af2eef6..88c1359 100644
--- a/tests/test_utils/tests.py
+++ b/tests/test_utils/tests.py
@@ -3,17 +3,28 @@ from __future__ import unicode_literals
 
 import unittest
 
+from django.conf import settings
 from django.db import connection
 from django.forms import EmailField, IntegerField
 from django.http import HttpResponse
 from django.template.loader import render_to_string
 from django.test import SimpleTestCase, TestCase, skipIfDBFeature, skipUnlessDBFeature
 from django.test.html import HTMLParseError, parse_html
-from django.test.utils import CaptureQueriesContext, IgnoreAllDeprecationWarningsMixin
+from django.test.utils import CaptureQueriesContext, IgnoreAllDeprecationWarningsMixin, override_settings
 from django.utils import six
 
 from .models import Person
 
+@override_settings(FOO='lol')
+class FooTestCase(TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        cls.foo = getattr(settings, 'FOO', 'BUG')
+
+    def test_foo(self):
+        self.assertNotEqual(self.foo, 'BUG')
+
 
 class SkippingTestCase(TestCase):
     def test_skip_unless_db_feature(self):