Issue #13374: The Windows bytes API has been deprecated in the os module. Use

Unicode filenames instead of bytes filenames to not depend on the ANSI code
page anymore and to support any filename.

Doc/whatsnew/3.3.rst

@@ -573,6 +573,10 @@ Porting Python code
   with sys.platform.startswith('linux'), or directly sys.platform == 'linux' if
   you don't need to support older Python versions.
 
+* Issue #13374: The Windows bytes API has been deprecated in the :mod:`os`
+  module. Use Unicode filenames instead of bytes filenames to not depend on the
+  ANSI code page anymore and to support any filename.
+
 Porting C code
 --------------
 

Lib/test/test_genericpath.py

@@ -2,11 +2,12 @@
 Tests common to genericpath, macpath, ntpath and posixpath
 """
 
-import unittest
-from test import support
-import os
 import genericpath
+import os
 import sys
+import unittest
+import warnings
+from test import support
 
 
 def safe_rmdir(dirname):
@@ -258,7 +259,9 @@ class CommonTest(GenericTest):
 
     def test_abspath(self):
         self.assertIn("foo", self.pathmodule.abspath("foo"))
-        self.assertIn(b"foo", self.pathmodule.abspath(b"foo"))
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            self.assertIn(b"foo", self.pathmodule.abspath(b"foo"))
 
         # Abspath returns bytes when the arg is bytes
         for path in (b'', b'foo', b'f\xf2\xf2', b'/foo', b'C:\\'):
@@ -266,7 +269,9 @@ class CommonTest(GenericTest):
 
     def test_realpath(self):
         self.assertIn("foo", self.pathmodule.realpath("foo"))
-        self.assertIn(b"foo", self.pathmodule.realpath(b"foo"))
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            self.assertIn(b"foo", self.pathmodule.realpath(b"foo"))
 
     def test_normpath_issue5827(self):
         # Make sure normpath preserves unicode
@@ -296,8 +301,10 @@ class CommonTest(GenericTest):
         "Mac OS X denies the creation of a directory with an invalid utf8 name")
     def test_nonascii_abspath(self):
         # Test non-ASCII, non-UTF8 bytes in the path.
-        with support.temp_cwd(b'\xe7w\xf0'):
-            self.test_abspath()
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            with support.temp_cwd(b'\xe7w\xf0'):
+                self.test_abspath()
 
 
 def test_main():

Lib/test/test_ntpath.py

 import ntpath
 import os
 import sys
+import unittest
+import warnings
 from test.support import TestFailed
 from test import support, test_genericpath
 from tempfile import TemporaryFile
-import unittest
 
 
 def tester(fn, wantResult):
@@ -21,7 +22,9 @@ def tester(fn, wantResult):
     fn = fn.replace('["', '[b"')
     fn = fn.replace(", '", ", b'")
     fn = fn.replace(', "', ', b"')
-    gotResult = eval(fn)
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", DeprecationWarning)
+        gotResult = eval(fn)
     if isinstance(wantResult, str):
         wantResult = wantResult.encode('ascii')
     elif isinstance(wantResult, tuple):

Lib/test/test_os.py

@@ -213,7 +213,9 @@ class StatAttributeTests(unittest.TestCase):
             fname = self.fname.encode(sys.getfilesystemencoding())
         except UnicodeEncodeError:
             self.skipTest("cannot encode %a for the filesystem" % self.fname)
-        self.check_stat_attributes(fname)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            self.check_stat_attributes(fname)
 
     def test_statvfs_attributes(self):
         if not hasattr(os, "statvfs"):
@@ -838,7 +840,9 @@ class LinkTests(unittest.TestCase):
         with open(file1, "w") as f1:
             f1.write("test")
 
-        os.link(file1, file2)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            os.link(file1, file2)
         with open(file1, "r") as f1, open(file2, "r") as f2:
             self.assertTrue(os.path.sameopenfile(f1.fileno(), f2.fileno()))
 
@@ -1160,8 +1164,10 @@ class Win32SymlinkTests(unittest.TestCase):
         self.assertNotEqual(os.lstat(link), os.stat(link))
 
         bytes_link = os.fsencode(link)
-        self.assertEqual(os.stat(bytes_link), os.stat(target))
-        self.assertNotEqual(os.lstat(bytes_link), os.stat(bytes_link))
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            self.assertEqual(os.stat(bytes_link), os.stat(target))
+            self.assertNotEqual(os.lstat(bytes_link), os.stat(bytes_link))
 
     def test_12084(self):
         level1 = os.path.abspath(support.TESTFN)
@@ -1619,6 +1625,35 @@ class ExtendedAttributeTests(unittest.TestCase):
         self._check_xattrs(getxattr, setxattr, removexattr, listxattr)
 
 
+@unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
+class Win32DeprecatedBytesAPI(unittest.TestCase):
+    def test_deprecated(self):
+        import nt
+        filename = os.fsencode(support.TESTFN)
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", DeprecationWarning)
+            for func, *args in (
+                (nt._getfullpathname, filename),
+                (nt._isdir, filename),
+                (os.access, filename, os.R_OK),
+                (os.chdir, filename),
+                (os.chmod, filename, 0o777),
+                (os.link, filename, filename),
+                (os.listdir, filename),
+                (os.lstat, filename),
+                (os.mkdir, filename),
+                (os.open, filename, os.O_RDONLY),
+                (os.rename, filename, filename),
+                (os.rmdir, filename),
+                (os.startfile, filename),
+                (os.stat, filename),
+                (os.symlink, filename, filename),
+                (os.unlink, filename),
+                (os.utime, filename),
+            ):
+                self.assertRaises(DeprecationWarning, func, *args)
+
+
 @support.reap_threads
 def test_main():
     support.run_unittest(
@@ -1643,6 +1678,7 @@ def test_main():
         TestSendfile,
         ProgramPriorityTests,
         ExtendedAttributeTests,
+        Win32DeprecatedBytesAPI,
     )
 
 if __name__ == "__main__":

Lib/test/test_pep277.py

 # Test the Unicode versions of normal file functions
 # open, os.open, os.stat. os.listdir, os.rename, os.remove, os.mkdir, os.chdir, os.rmdir
-import sys, os, unittest
+import os
+import sys
+import unittest
+import warnings
 from unicodedata import normalize
 from test import support
 
@@ -155,7 +158,9 @@ class UnicodeFileTests(unittest.TestCase):
     @unittest.skipIf(sys.platform == 'darwin', 'irrelevant test on Mac OS X')
     def test_listdir(self):
         sf0 = set(self.files)
-        f1 = os.listdir(support.TESTFN.encode(sys.getfilesystemencoding()))
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            f1 = os.listdir(support.TESTFN.encode(sys.getfilesystemencoding()))
         f2 = os.listdir(support.TESTFN)
         sf2 = set(os.path.join(support.TESTFN, f) for f in f2)
         self.assertEqual(sf0, sf2, "%a != %a" % (sf0, sf2))

Lib/test/test_posixpath.py

-import unittest
-from test import support, test_genericpath
-
-import posixpath
 import os
+import posixpath
 import sys
+import unittest
+import warnings
 from posixpath import realpath, abspath, dirname, basename
+from test import support, test_genericpath
 
 try:
     import posix
@@ -231,7 +231,9 @@ class PosixPathTest(unittest.TestCase):
 
     def test_ismount(self):
         self.assertIs(posixpath.ismount("/"), True)
-        self.assertIs(posixpath.ismount(b"/"), True)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", DeprecationWarning)
+            self.assertIs(posixpath.ismount(b"/"), True)
 
     def test_ismount_non_existent(self):
         # Non-existent mountpoint.

Misc/NEWS

@@ -374,6 +374,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #13374: The Windows bytes API has been deprecated in the os module. Use
+  Unicode filenames instead of bytes filenames to not depend on the ANSI code
+  page anymore and to support any filename.
+
 - Issue #13297: Use bytes type to send and receive binary data through XMLRPC.
 
 - Issue #6397: Support "/dev/poll" polling objects in select module,