diff -r 63b45c959a2a Lib/test/test_os.py
--- a/Lib/test/test_os.py	Sun Nov 04 07:00:04 2012 +0200
+++ b/Lib/test/test_os.py	Sun Nov 04 21:19:57 2012 -0500
@@ -49,12 +49,48 @@
 else:
     USING_LINUXTHREADS = False
 
-# Tests creating TESTFN
+# Tests creating TESTFN and os.rename
 class FileTests(unittest.TestCase):
     def setUp(self):
         if os.path.exists(support.TESTFN):
             os.unlink(support.TESTFN)
-    tearDown = setUp
+
+        self.rename_src_file = "%s_%d_tmp" % ("test_rename_src_file", \
+            os.getpid())
+        if os.path.exists(self.rename_src_file):
+            os.unlink(self.rename_src_file)
+        self.rename_dst_file = "%s_%d_tmp" % ("test_rename_dst_file", \
+            os.getpid())
+        if os.path.exists(self.rename_dst_file):
+            os.unlink(self.rename_dst_file)            
+        self.rename_dst_directory = "%s_%d_tmp" % \
+            ("test_rename_dst_directory", os.getpid())
+        if os.path.exists(self.rename_dst_directory + "/file.txt"):
+            os.unlink(self.rename_dst_directory + "/file.txt")
+        if os.path.exists(self.rename_dst_directory):
+            os.rmdir(self.rename_dst_directory)            
+        self.rename_src_directory = "%s_%d_tmp" % \
+            ("test_src_directory", os.getpid())
+        if os.path.exists(self.rename_src_directory + "/file.txt"):
+            os.unlink(self.rename_src_directory + "/file.txt")
+        if (os.path.exists(self.rename_src_directory)):
+            os.rmdir(self.rename_src_directory)
+
+    def tearDown(self):
+        if os.path.exists(support.TESTFN):
+            os.unlink(support.TESTFN)                    
+        if os.path.exists(self.rename_src_file):
+            os.unlink(self.rename_src_file)           
+        if os.path.exists(self.rename_dst_file):
+            os.unlink(self.rename_dst_file)
+        if os.path.exists(self.rename_dst_directory + "/file.txt"):
+            os.unlink(self.rename_dst_directory + "/file.txt")
+        if os.path.exists(self.rename_dst_directory):
+            os.rmdir(self.rename_dst_directory)
+        if os.path.exists(self.rename_src_directory + "/file.txt"):
+            os.unlink(self.rename_src_directory + "/file.txt")
+        if (os.path.exists(self.rename_src_directory)):
+            os.rmdir(self.rename_src_directory)            
 
     def test_access(self):
         f = os.open(support.TESTFN, os.O_CREAT|os.O_RDWR)
@@ -90,6 +126,344 @@
         new = sys.getrefcount(path)
         self.assertEqual(old, new)
 
+    # http://bugs.python.org/issue16278
+    # the os.rename docuemntation states:
+    # "On Unix, if dst exists and is a file, it will be replaced silently if
+    # the user has permission."
+    #
+    # "On Windows, if dst already exists, OSError will be raised even if it
+    # is a file; there may be no way to implement an atomic rename when dst
+    # names an existing file."
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                           (sys.platform.startswith == 'linux') or \
+                           (sys.platform == 'win32') ), \
+                          'test specific to windows or linux or darwin only')
+    def test_rename_src_file_dest_file_exist(self):
+        src = self.rename_src_file
+        dst = self.rename_dst_file
+        fd = os.open(src, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)
+        fd = os.open(dst, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"dst file already exists and has data\n")
+        os.close(fd)
+        if ((sys.platform == 'darwin') or (sys.platform.startswith == "linux")):
+            os.rename(src, dst)       
+            with open(dst, "rb") as fobj:
+                self.assertEqual(fobj.read().splitlines(),
+                    [b"beans", b"bacon", b"eggs", b"spam"])
+        elif (sys.platform == 'win'):
+            self.assertRaises(OSError, os.rename, src, dst)       
+            with open(dst, "rb") as fobj:
+                self.assertEqual(fobj.read(),
+                    b"destination file already exists and has data\n")
+            
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_file_dst_not_exist(self):
+        src = self.rename_src_file
+        dst = self.rename_dst_file
+        fd = os.open(src, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)
+        os.rename(src, dst)
+        with open(dst, "rb") as fobj:
+            self.assertEqual(fobj.read().splitlines(),
+                [b"beans", b"bacon", b"eggs", b"spam"])
+
+    # http://bugs.python.org/issue16278
+    # the os.rename documentation should state:
+    # Rename the file src to dst. If src is a file and dst is a
+    # directory that is empty or not empty, OSError will be raised.
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_file_dst_directory_empty(self):
+        src = self.rename_src_file
+        dst = self.rename_dst_directory
+        fd = os.open(src, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)
+        os.mkdir(dst)
+        self.assertRaises(OSError, os.rename, src, dst)                         
+
+    # http://bugs.python.org/issue16278
+    # the os.rename documentation should state:
+    # Rename the file or directory src to dst. If src is a file and dst is a
+    # directory that is empty or not empty, OSError will be raised.
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_file_dst_directory_not_empty(self):
+        src = self.rename_src_file
+        dst = self.rename_dst_directory
+        fd = os.open(src, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)
+        os.mkdir(dst)
+        fd = os.open(dst + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"dst file already exists and has data")
+        os.close(fd)
+        self.assertRaises(OSError, os.rename, src, dst)       
+        with open(dst + "/file.txt", "rb") as fobj:
+            self.assertEqual(fobj.read(),
+                b"dst file already exists and has data")
+
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')    
+    def test_rename_src_directory_empty_dst_file_exist(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_file
+        os.mkdir(src)
+        fd = os.open(dst, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"dst file already exists and has data")
+        os.close(fd)
+        self.assertRaises(OSError, os.rename, src, dst)
+        with open(dst, "rb") as fobj:
+            self.assertEqual(fobj.read(),
+                b"dst file already exists and has data")
+
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_directory_empty_dst_not_exist(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_directory
+        os.mkdir(src)
+        os.rename(src, dst)
+        self.assertEqual(os.path.exists(dst), True)
+        self.assertEqual(os.path.exists(src), False)
+
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')
+    def test_rename_src_directory_empty_dst_directory_empty(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_directory
+        os.mkdir(src)
+        os.mkdir(dst)
+        if ((sys.platform.startswith == 'linux') or (sys.platform == 'darwin')):
+            os.rename(src, dst)
+            self.assertEqual(os.path.exists(dst), True)
+            self.assertEqual(os.path.exists(src), False)
+        elif (sys.platform == 'win32'):
+            self.assertRaises(FileExistsError, os.rename, src, dst)
+            # both src and dst will still be intact on windows
+            self.assertEqual(os.path.exists(dst), True) 
+            self.assertEqual(os.path.exists(src), True) 
+			
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')    
+    def test_rename_src_directory_empty_dst_directory_not_empty(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_directory
+        os.mkdir(src)
+        os.mkdir(dst)
+        fd = os.open(dst + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"destination file already exists and has data")
+        os.close(fd)        
+        self.assertRaises(OSError, os.rename, src, dst)
+        # destination file should be in tact
+        with open(dst + "/file.txt", "rb") as fobj:
+            self.assertEqual(fobj.read(),
+                b"destination file already exists and has data")
+
+    # http://bugs.python.org/issue16278
+    @support.cpython_only   
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_directory_not_empty_dst_file_exist(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_file
+        os.mkdir(src)
+        fd = os.open(src + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)        
+        fd = os.open(dst, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"dst file already exists and has data")
+        os.close(fd)
+        self.assertRaises(OSError, os.rename, src, dst)
+        with open(dst, "rb") as fobj:
+            self.assertEqual(fobj.read(),
+                b"dst file already exists and has data")
+
+    # http://bugs.python.org/issue16278
+    @support.cpython_only    
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_directory_not_empty_dst_not_exist(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_directory
+        os.mkdir(src)
+        fd = os.open(src + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)
+        os.rename(src, dst)
+        with open(dst + "/file.txt", "rb") as fobj:
+            self.assertEqual(fobj.read().splitlines(),
+                [b"beans", b"bacon", b"eggs", b"spam"])
+        
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')    
+    def test_rename_src_directory_not_empty_dst_directory_empty(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_directory
+        os.mkdir(src)
+        fd = os.open(src + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)
+        os.mkdir(dst)
+        if ((sys.platform.startswith == 'linux') or (sys.platform == 'darwin')):        
+            os.rename(src, dst)
+            with open(dst + "/file.txt", "rb") as fobj:
+                self.assertEqual(fobj.read().splitlines(),
+                    [b"beans", b"bacon", b"eggs", b"spam"])
+        elif (sys.platform == 'win32'):
+            self.assertRaises(FileExistsError, os.rename, src, dst)
+            # both src and dst will still be intact on windows
+            self.assertEqual(os.path.exists(dst), True) 
+            self.assertEqual(os.path.exists(src), True)         
+            
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')        
+    def test_rename_src_directory_not_empty_dst_directory_not_empty(self):
+        src = self.rename_src_directory
+        dst = self.rename_dst_directory
+        os.mkdir(src)
+        fd = os.open(src + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"beans\n")
+        os.write(fd, b"bacon\n")
+        os.write(fd, b"eggs\n")
+        os.write(fd, b"spam\n")
+        os.close(fd)
+        os.mkdir(dst)
+        fd = os.open(dst + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"destination file already exists and has data")
+        os.close(fd)        
+        self.assertRaises(OSError, os.rename, src, dst)
+        # destination file should be in tact
+        with open(dst + "/file.txt", "rb") as fobj:
+            self.assertEqual(fobj.read(),
+                b"destination file already exists and has data")
+
+    # http://bugs.python.org/issue16278
+    @support.cpython_only
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_file_or_directory_not_exist_dst_file_exist(self):
+        src = self.rename_src_file + "does_not_exist"
+        dst = self.rename_dst_file
+        fd = os.open(dst, os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"destination file already exists and has data")
+        os.close(fd)        
+        self.assertRaises(OSError, os.rename, src, dst)
+        # destination file should be in tact
+        with open(dst, "rb") as fobj:
+            self.assertEqual(fobj.read(),
+                b"destination file already exists and has data")
+        
+    # http://bugs.python.org/issue16278
+    @support.cpython_only        
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_file_or_directory_not_exist_dst_not_exist(self):
+        src = self.rename_src_file + "does_not_exist"
+        dst = self.rename_dst_file + "does_not_exist"
+        self.assertRaises(OSError, os.rename, src, dst)
+
+    # http://bugs.python.org/issue16278
+    @support.cpython_only       
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_file_or_directory_not_exist_dst_directory_empty(self):
+        src = self.rename_src_file + "does_not_exist"
+        dst = self.rename_dst_directory
+        os.mkdir(dst)
+        self.assertRaises(OSError, os.rename, src, dst)
+        self.assertEqual(os.path.exists(dst), True)
+        
+    # http://bugs.python.org/issue16278
+    @support.cpython_only   
+    @unittest.skipUnless(( (sys.platform == 'darwin') or \
+                        (sys.platform.startswith == 'linux') or \
+                        (sys.platform == 'win32') ), \
+                        'test specific to windows or linux or darwin only')     
+    def test_rename_src_file_or_directory_not_exist_dst_directory_not_empty(self):
+        src = self.rename_src_file + "does_not_exist"
+        dst = self.rename_dst_directory
+        os.mkdir(dst)
+        fd = os.open(dst + "/file.txt", os.O_CREAT | os.O_WRONLY)
+        os.write(fd, b"destination file already exists and has data")
+        os.close(fd)        
+        self.assertRaises(OSError, os.rename, src, dst)
+        self.assertEqual(os.path.exists(dst), True)
+        # destination file should be in tact
+        with open(dst + "/file.txt", "rb") as fobj:
+            self.assertEqual(fobj.read(),
+                b"destination file already exists and has data")
+                    
     def test_read(self):
         with open(support.TESTFN, "w+b") as fobj:
             fobj.write(b"spam")