Use locale.getencoding instead of getpreferredencoding

- from Python 3.11 on, this is the preferred version
- fixes pytest-dev#957

.github/workflows/testsuite.yml

@@ -21,6 +21,8 @@ jobs:
 
   tests:
     runs-on: ${{ matrix.os }}
+    env:
+      PYTHONWARNDEFAULTENCODING: true
     strategy:
       fail-fast: false
       matrix:

CHANGES.md

@@ -7,6 +7,7 @@ The released versions correspond to PyPI releases.
 * Fixed a specific problem on reloading a pandas-related module (see [#947](../../issues/947)),
   added possibility for unload hooks for specific modules
 * Use this also to reload django views (see [#932](../../issues/932))
+* Fixed `EncodingWarning` for Python >= 3.11 (see [#957](../../issues/957))
 
 ## [Version 5.3.5](https://pypi.python.org/pypi/pyfakefs/5.3.5) (2024-01-30)
 Fixes a regression.

pyfakefs/fake_file.py

@@ -16,7 +16,6 @@
 """
 import errno
 import io
-import locale
 import os
 import sys
 from stat import (
@@ -52,6 +51,7 @@
     real_encoding,
     AnyPath,
     AnyString,
+    get_locale_encoding,
 )
 
 if TYPE_CHECKING:
@@ -190,7 +190,7 @@ def contents(self) -> Optional[str]:
         """Return the contents as string with the original encoding."""
         if isinstance(self.byte_contents, bytes):
             return self.byte_contents.decode(
-                self.encoding or locale.getpreferredencoding(False),
+                self.encoding or get_locale_encoding(),
                 errors=self.errors,
             )
         return None
@@ -263,7 +263,7 @@ def _encode_contents(self, contents: Union[str, bytes, None]) -> Optional[bytes]
         if is_unicode_string(contents):
             contents = bytes(
                 cast(str, contents),
-                self.encoding or locale.getpreferredencoding(False),
+                self.encoding or get_locale_encoding(),
                 self.errors,
             )
         return cast(bytes, contents)
@@ -745,7 +745,7 @@ def __init__(
         self._use_line_buffer = not binary and buffering == 1
 
         contents = file_object.byte_contents
-        self._encoding = encoding or locale.getpreferredencoding(False)
+        self._encoding = encoding or get_locale_encoding()
         errors = errors or "strict"
         self._io: Union[BinaryBufferIO, TextBufferIO] = (
             BinaryBufferIO(contents)

pyfakefs/helpers.py

@@ -109,6 +109,12 @@ def is_unicode_string(val: Any) -> bool:
     return hasattr(val, "encode")
 
 
+def get_locale_encoding():
+    if sys.version_info >= (3, 11):
+        return locale.getencoding()
+    return locale.getpreferredencoding(False)
+
+
 @overload
 def make_string_path(dir_name: AnyStr) -> AnyStr:
     ...
@@ -127,15 +133,15 @@ def to_string(path: Union[AnyStr, Union[str, bytes]]) -> str:
     """Return the string representation of a byte string using the preferred
     encoding, or the string itself if path is a str."""
     if isinstance(path, bytes):
-        return path.decode(locale.getpreferredencoding(False))
+        return path.decode(get_locale_encoding())
     return path
 
 
 def to_bytes(path: Union[AnyStr, Union[str, bytes]]) -> bytes:
     """Return the bytes representation of a string using the preferred
     encoding, or the byte string itself if path is a byte string."""
     if isinstance(path, str):
-        return bytes(path, locale.getpreferredencoding(False))
+        return bytes(path, get_locale_encoding())
     return path
 
 
@@ -181,7 +187,7 @@ def matching_string(  # type: ignore[misc]
     if string is None:
         return string
     if isinstance(matched, bytes) and isinstance(string, str):
-        return string.encode(locale.getpreferredencoding(False))
+        return string.encode(get_locale_encoding())
     return string  # pytype: disable=bad-return-type
 
 

pyfakefs/tests/fake_open_test.py

@@ -17,15 +17,14 @@
 
 import errno
 import io
-import locale
 import os
 import stat
 import sys
 import time
 import unittest
 
 from pyfakefs import fake_filesystem, helpers
-from pyfakefs.helpers import is_root, IS_PYPY
+from pyfakefs.helpers import is_root, IS_PYPY, get_locale_encoding
 from pyfakefs.fake_io import FakeIoModule
 from pyfakefs.fake_filesystem_unittest import PatchMode
 from pyfakefs.tests.test_utils import RealFsTestCase
@@ -124,9 +123,7 @@ def test_write_str_read_bytes(self):
             self.skipTest("This test does not work with an ASCII locale")
         with self.open(file_path, "rb") as f:
             contents = f.read()
-        self.assertEqual(
-            str_contents, contents.decode(locale.getpreferredencoding(False))
-        )
+        self.assertEqual(str_contents, contents.decode(get_locale_encoding()))
 
     def test_open_valid_file(self):
         contents = [