diff -r 3d1cdbd76fbe Lib/test/test_exceptions.py
--- a/Lib/test/test_exceptions.py	Tue Aug 16 22:28:23 2011 -0500
+++ b/Lib/test/test_exceptions.py	Tue Aug 23 18:03:15 2011 -0700
@@ -5,6 +5,7 @@
 import unittest
 import pickle
 import weakref
+import errno
 
 from test.support import (TESTFN, unlink, run_unittest, captured_output,
                           gc_collect, cpython_only, no_tracing)
@@ -790,6 +791,15 @@
             self.fail("RuntimeError not raised")
         self.assertEqual(wr(), None)
 
+    def test_ENOTDIR_errno(self):
+        # os.listdir on file should raise OSError with errno ENOTDIR
+        try:
+            os.listdir(__file__)
+        except OSError as e:
+            self.assertEqual(errno.ENOTDIR, e.errno)
+        else:
+            self.fail("OSError not raised")
+
 def test_main():
     run_unittest(ExceptionTests)