diff -r 9e54def97a5e Lib/test/test_sys.py
--- a/Lib/test/test_sys.py	Sat Sep 28 21:24:43 2013 +0300
+++ b/Lib/test/test_sys.py	Sat Sep 28 23:51:24 2013 +0300
@@ -9,6 +9,7 @@
 import gc
 import sysconfig
 
+
 # count the number of test runs, used to create unique
 # strings to intern in test_intern()
 numruns = 0
@@ -525,60 +526,44 @@
     def test_clear_type_cache(self):
         sys._clear_type_cache()
 
+    def check_ioencoding(self, env, expected_enc, expected_err):
+        cmd = ('import sys; print(sys.stdin.encoding, sys.stdin.errors, '
+                                 'sys.stdout.encoding, sys.stdout.errors, '
+                                 'sys.stderr.encoding, sys.stderr.errors)')
+        p = subprocess.Popen([sys.executable, '-c', cmd],
+                             stdout=subprocess.PIPE,
+                             env=env)
+        expected = ' '.join((expected_enc, expected_err,
+                             expected_enc, expected_err,
+                             expected_enc, 'backslashreplace')) + os.linesep
+        self.assertEqual(p.communicate()[0].strip(),
+            (expected.encode(expected_enc, expected_err).strip()))
+
     def test_ioencoding(self):
         env = dict(os.environ)
 
-        # Test character: cent sign, encoded as 0x4A (ASCII J) in CP424,
-        # not representable in ASCII.
-
         env["PYTHONIOENCODING"] = "cp424"
-        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
-                             stdout = subprocess.PIPE, env=env)
-        out = p.communicate()[0].strip()
-        expected = ("\xa2" + os.linesep).encode("cp424")
-        self.assertEqual(out, expected)
+        self.check_ioencoding(env, 'cp424', 'strict')
 
         env["PYTHONIOENCODING"] = "ascii:replace"
-        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
-                             stdout = subprocess.PIPE, env=env)
-        out = p.communicate()[0].strip()
-        self.assertEqual(out, b'?')
+        self.check_ioencoding(env, 'ascii', 'replace')
 
         env["PYTHONIOENCODING"] = "ascii"
-        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
-                             stdout=subprocess.PIPE, stderr=subprocess.PIPE,
-                             env=env)
-        out, err = p.communicate()
-        self.assertEqual(out, b'')
-        self.assertIn(b'UnicodeEncodeError:', err)
-        self.assertIn(rb"'\xa2'", err)
+        self.check_ioencoding(env, 'ascii', 'strict')
 
         env["PYTHONIOENCODING"] = "ascii:"
-        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xa2))'],
-                             stdout=subprocess.PIPE, stderr=subprocess.PIPE,
-                             env=env)
-        out, err = p.communicate()
-        self.assertEqual(out, b'')
-        self.assertIn(b'UnicodeEncodeError:', err)
-        self.assertIn(rb"'\xa2'", err)
+        self.check_ioencoding(env, 'ascii', 'strict')
 
+        import locale
+        encoding = locale.getpreferredencoding()
         env["PYTHONIOENCODING"] = ":surrogateescape"
-        p = subprocess.Popen([sys.executable, "-c", 'print(chr(0xdcbd))'],
-                             stdout=subprocess.PIPE, env=env)
-        out = p.communicate()[0].strip()
-        self.assertEqual(out, b'\xbd')
-
-    @unittest.skipUnless(test.support.FS_NONASCII,
-                         'requires OS support of non-ASCII encodings')
-    def test_ioencoding_nonascii(self):
-        env = dict(os.environ)
+        self.check_ioencoding(env, encoding, 'surrogateescape')
 
         env["PYTHONIOENCODING"] = ""
-        p = subprocess.Popen([sys.executable, "-c",
-                                'print(%a)' % test.support.FS_NONASCII],
-                                stdout=subprocess.PIPE, env=env)
-        out = p.communicate()[0].strip()
-        self.assertEqual(out, os.fsencode(test.support.FS_NONASCII))
+        self.check_ioencoding(env, encoding, 'strict')
+
+        del env["PYTHONIOENCODING"]
+        self.check_ioencoding(env, encoding, 'strict')
 
     @unittest.skipIf(sys.base_prefix != sys.prefix,
                      'Test is not venv-compatible')