diff -r abcf17bc5eae Lib/test/test_os.py
--- a/Lib/test/test_os.py	Tue Jun 17 00:34:56 2014 -0700
+++ b/Lib/test/test_os.py	Wed Jun 18 22:16:55 2014 +0700
@@ -4,6 +4,7 @@
 
 import os
 import errno
+import getpass
 import unittest
 import warnings
 import sys
@@ -43,6 +44,14 @@
     import _winapi
 except ImportError:
     _winapi = None
+try:
+    import grp
+except ImportError:
+    grp = None
+try:
+    import pwd
+except ImportError:
+    pwd = None
 
 from test.script_helper import assert_python_ok
 
@@ -68,6 +77,29 @@
 # Issue #14110: Some tests fail on FreeBSD if the user is in the wheel group.
 HAVE_WHEEL_GROUP = sys.platform.startswith('freebsd') and os.getgid() == 0
 
+def root_in_posix():
+    if hasattr(os, 'geteuid'):
+        return os.geteuid() == 0
+    else:
+        # On Windows
+        return False
+
+if grp is not None:
+    # 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)
+else:
+    groups = []
+
+if pwd is not None:
+    # Get all users
+    all_users = [u.pw_uid for u in pwd.getpwall()]
+else:
+    all_users = []
+
+
 # Tests creating TESTFN
 class FileTests(unittest.TestCase):
     def setUp(self):
@@ -920,6 +952,46 @@
         self.assertIsNone(os.chown(support.TESTFN, uid, gid))
         self.assertIsNone(os.chown(support.TESTFN, -1, -1))
 
+    @unittest.skipUnless(hasattr(os, 'chown') and len(groups) > 1,
+                         'test needs os.chown and groups more than one')
+    def test_chown(self):
+        gid_1, gid_2 = groups[:2]
+        uid = os.stat(support.TESTFN).st_uid
+        os.chown(support.TESTFN, uid, gid_1)
+        gid = os.stat(support.TESTFN).st_gid
+        self.assertEqual(gid, gid_1)
+        os.chown(support.TESTFN, uid, gid_2)
+        gid = os.stat(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):
+        uid_1, uid_2 = all_users[:2]
+        gid = os.stat(support.TESTFN).st_gid
+        os.chown(support.TESTFN, uid_1, gid)
+        uid = os.stat(support.TESTFN).st_uid
+        self.assertEqual(uid, uid_1)
+        os.chown(support.TESTFN, uid_2, gid)
+        uid = os.stat(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):
+        uid_1, uid_2 = all_users[:2]
+        gid = os.stat(support.TESTFN).st_gid
+        with self.assertRaises(PermissionError) as cx:
+            os.chown(support.TESTFN, uid_1, gid)
+            os.chown(support.TESTFN, uid_2, gid)
+        self.assertEqual(str(cx.exception),
+                         "[Errno 1] Operation not permitted: '%s'" %
+                         support.TESTFN)
+
     def test_exist_ok_s_isgid_directory(self):
         path = os.path.join(support.TESTFN, 'dir1')
         S_ISGID = stat.S_ISGID