bpo-29240: PEP 540: Add a new UTF-8 Mode (#855)

* Add -X utf8 command line option, PYTHONUTF8 environment variable
  and a new sys.flags.utf8_mode flag.
* If the LC_CTYPE locale is "C" at startup: enable automatically the
  UTF-8 mode.
* Add _winapi.GetACP(). encodings._alias_mbcs() now calls
  _winapi.GetACP() to get the ANSI code page
* locale.getpreferredencoding() now returns 'UTF-8' in the UTF-8
  mode. As a side effect, open() now uses the UTF-8 encoding by
  default in this mode.
* Py_DecodeLocale() and Py_EncodeLocale() now use the UTF-8 encoding
  in the UTF-8 Mode.
* Update subprocess._args_from_interpreter_flags() to handle -X utf8
* Skip some tests relying on the current locale if the UTF-8 mode is
  enabled.
* Add test_utf8mode.py.
* _Py_DecodeUTF8_surrogateescape() gets a new optional parameter to
  return also the length (number of wide characters).
* pymain_get_global_config() and pymain_set_global_config() now
  always copy flag values, rather than only copying if the new value
  is greater than the old value.

1 files changed, 2 insertions, 8 deletions

diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index eb21a39..a59a5e2 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -5,6 +5,7 @@ import locale
 import sys
 import unittest
 import encodings
+from unittest import mock
 
 from test import support
 
@@ -3180,16 +3181,9 @@ class CodePageTest(unittest.TestCase):
     def test_mbcs_alias(self):
         # Check that looking up our 'default' codepage will return
         # mbcs when we don't have a more specific one available
-        import _bootlocale
-        def _get_fake_codepage(*a):
-            return 'cp123'
-        old_getpreferredencoding = _bootlocale.getpreferredencoding
-        _bootlocale.getpreferredencoding = _get_fake_codepage
-        try:
+        with mock.patch('_winapi.GetACP', return_value=123):
             codec = codecs.lookup('cp123')
             self.assertEqual(codec.name, 'mbcs')
-        finally:
-            _bootlocale.getpreferredencoding = old_getpreferredencoding
 
 
 class ASCIITest(unittest.TestCase):