Fixed #13092 -- Added support for the "in" operator when dealing with context lists. Thanks to clelland for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13510 bcc190cf-cafb-0310-a4f2-bffc1f526a37

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):
     """