diff --git a/django/test/utils.py b/django/test/utils.py
index d178c9b29c6..be586c75a6d 100644
--- a/django/test/utils.py
+++ b/django/test/utils.py
@@ -60,6 +60,16 @@ class ContextList(list):
             return False
         return True
 
+    def keys(self):
+        """
+        Flattened keys of subcontexts.
+        """
+        keys = set()
+        for subcontext in self:
+            for dict in subcontext:
+                keys |= set(dict.keys())
+        return keys
+
 
 def instrumented_test_render(self, context):
     """
diff --git a/tests/test_client_regress/tests.py b/tests/test_client_regress/tests.py
index 654f65235a9..dc656c127dd 100644
--- a/tests/test_client_regress/tests.py
+++ b/tests/test_client_regress/tests.py
@@ -6,9 +6,8 @@ from __future__ import unicode_literals
 
 import os
 
-from django.conf import settings
 from django.core.urlresolvers import reverse
-from django.template import (TemplateDoesNotExist, TemplateSyntaxError,
+from django.template import (TemplateSyntaxError,
     Context, Template, loader)
 import django.template.context
 from django.test import Client, TestCase
@@ -897,6 +896,21 @@ class ContextTests(TestCase):
         except KeyError as e:
             self.assertEqual(e.args[0], 'does-not-exist')
 
+    def test_contextlist_keys(self):
+        c1 = Context()
+        c1.update({'hello': 'world', 'goodbye': 'john'})
+        c1.update({'hello': 'dolly', 'dolly': 'parton'})
+        c2 = Context()
+        c2.update({'goodbye': 'world', 'python': 'rocks'})
+        c2.update({'goodbye': 'dolly'})
+
+        l = ContextList([c1, c2])
+        # None, True and False are builtins of BaseContext, and present
+        # in every Context without needing to be added.
+        self.assertEqual(set(['None', 'True', 'False', 'hello', 'goodbye',
+                              'python', 'dolly']),
+                         l.keys())
+
     def test_15368(self):
         # Need to insert a context processor that assumes certain things about
         # the request instance. This triggers a bug caused by some ways of