diff --git a/django/test/utils.py b/django/test/utils.py
index b6ab39901b..404d130297 100644
--- a/django/test/utils.py
+++ b/django/test/utils.py
@@ -19,6 +19,12 @@ class ContextList(list):
         else:
             return super(ContextList, self).__getitem__(key)
 
+    def __contains__(self, key):
+        try:
+            value = self[key]
+        except KeyError:
+            return False
+        return True
 
 def instrumented_test_render(self, context):
     """
diff --git a/tests/regressiontests/test_client_regress/models.py b/tests/regressiontests/test_client_regress/models.py
index 6da7ae4445..a740237321 100644
--- a/tests/regressiontests/test_client_regress/models.py
+++ b/tests/regressiontests/test_client_regress/models.py
@@ -619,6 +619,7 @@ class ContextTests(TestCase):
         "Context variables can be retrieved from a single context"
         response = self.client.get("/test_client_regress/request_data/", data={'foo':'whiz'})
         self.assertEqual(response.context.__class__, Context)
+        self.assertTrue('get-foo' in response.context)
         self.assertEqual(response.context['get-foo'], 'whiz')
         self.assertEqual(response.context['request-foo'], 'whiz')
         self.assertEqual(response.context['data'], 'sausage')
@@ -634,6 +635,7 @@ class ContextTests(TestCase):
         response = self.client.get("/test_client_regress/request_data_extended/", data={'foo':'whiz'})
         self.assertEqual(response.context.__class__, ContextList)
         self.assertEqual(len(response.context), 2)
+        self.assertTrue('get-foo' in response.context)
         self.assertEqual(response.context['get-foo'], 'whiz')
         self.assertEqual(response.context['request-foo'], 'whiz')
         self.assertEqual(response.context['data'], 'bacon')