diff -r c3df5d3e627f Lib/test/test_doctest.py
--- a/Lib/test/test_doctest.py	Sat Jul 27 21:31:13 2013 -0500
+++ b/Lib/test/test_doctest.py	Sat Jul 27 21:32:04 2013 -0500
@@ -762,6 +762,18 @@
         6
     ok
     TestResults(failed=1, attempted=3)
+
+
+Compare `DocTestCaseRunner`:
+
+    >>> class CustomDocTestRunner(doctest.DocTestRunner):
+    ...    pass
+    >>> DocTestCase = doctest.DocTestCase
+    >>> test_case = DocTestCase(test, runner=CustomDocTestRunner)
+    >>> test_case._dt_runner == CustomDocTestRunner
+    True
+    >>> test_case._dt_runner
+    <class 'test.test_doctest.CustomDocTestRunner'>
 """
     def verbose_flag(): r"""
 The `verbose` flag makes the test runner generate more detailed