diff -r 3598805d7636 Lib/test/test_os.py
--- a/Lib/test/test_os.py	Wed Dec 25 22:26:59 2013 -0500
+++ b/Lib/test/test_os.py	Thu Dec 26 18:26:53 2013 +0800
@@ -4,6 +4,9 @@
 
 import os
 import errno
+import getpass
+import grp
+import pwd
 import unittest
 import warnings
 import sys
@@ -23,6 +26,22 @@
 warnings.filterwarnings("ignore", "tempnam", RuntimeWarning, __name__)
 warnings.filterwarnings("ignore", "tmpnam", RuntimeWarning, __name__)
 
+def root_in_posix():
+    if hasattr(os, 'getuid'):
+        return os.getuid() == 0
+    else:
+        return False
+
+# Get groups whom the process' user belongs to
+groups = [g.gr_gid for g in grp.getgrall() if getpass.getuser() in g.gr_mem]
+process_gid = os.getgid()
+if process_gid not in groups:
+    groups.append(process_gid)
+
+# Get all users
+all_users = [u.pw_uid for u in pwd.getpwall()]
+
+
 # Tests creating TESTFN
 class FileTests(unittest.TestCase):
     def setUp(self):
@@ -64,6 +83,52 @@
         new = sys.getrefcount(path)
         self.assertEqual(old, new)
 
+    @unittest.skipUnless(hasattr(os, 'chown') and len(groups) > 1,
+                         'test needs os.chown and groups more than one')
+    def test_chown(self):
+        f = os.open(test_support.TESTFN, os.O_CREAT|os.O_RDWR)
+        os.close(f)
+        gid_1, gid_2 = groups[0:2]
+        uid = os.stat(test_support.TESTFN).st_uid
+        os.chown(test_support.TESTFN, uid, gid_1)
+        gid = os.stat(test_support.TESTFN).st_gid
+        self.assertEqual(gid, gid_1)
+        os.chown(test_support.TESTFN, uid, gid_2)
+        gid = os.stat(test_support.TESTFN).st_gid
+        self.assertEqual(gid, gid_2)
+
+    @unittest.skipUnless(hasattr(os, 'chown') and root_in_posix() and
+                         len(all_users) > 1,
+                         "test needs os.chown, root in posix, and users more "
+                         "than 1")
+    def test_chown_with_root(self):
+        f = os.open(test_support.TESTFN, os.O_CREAT|os.O_RDWR)
+        os.close(f)
+        uid_1, uid_2 = all_users[0:2]
+        gid = os.stat(test_support.TESTFN).st_gid
+        os.chown(test_support.TESTFN, uid_1, gid)
+        uid = os.stat(test_support.TESTFN).st_uid
+        self.assertEqual(uid, uid_1)
+        os.chown(test_support.TESTFN, uid_2, gid)
+        uid = os.stat(test_support.TESTFN).st_uid
+        self.assertEqual(uid, uid_2)
+
+    @unittest.skipUnless(hasattr(os, 'chown') and not root_in_posix() and
+                         len(all_users) > 1,
+                         "test needs os.chown, non-root account in posix, and "
+                         "users more than 1")
+    def test_chown_without_permission(self):
+        f = os.open(test_support.TESTFN, os.O_CREAT|os.O_RDWR)
+        os.close(f)
+        uid_1, uid_2 = all_users[0:2]
+        gid = os.stat(test_support.TESTFN).st_gid
+        with self.assertRaises(OSError) as cx:
+            os.chown(test_support.TESTFN, uid_1, gid)
+            os.chown(test_support.TESTFN, uid_2, gid)
+        self.assertEqual(str(cx.exception),
+                         "[Errno 1] Operation not permitted: '%s'" %
+                         test_support.TESTFN)
+
 
 class TemporaryFileTests(unittest.TestCase):
     def setUp(self):