Fix patching open for Python 3.12

- add patching _io, as this is used for io
- add workaround for calling the real open_code
  (does not work yet under Windows)
- add Python 3.12 to supported Python versions
- fixes #836

Author: mrbean-bremen

.github/workflows/testsuite.yml

@@ -25,7 +25,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macOS-latest, windows-latest]
-        python-version: [3.7, 3.8, 3.9, "3.10", "3.11", "3.12-dev"]
+        python-version: [3.7, 3.8, 3.9, "3.10", "3.11", "3.12"]
         include:
           - python-version: "pypy-3.7"
             os: ubuntu-latest

CHANGES.md

@@ -3,11 +3,15 @@ The released versions correspond to PyPI releases.
 
 ## Unreleased
 
+### Changes
+* add official support for Python 3.12
+
 ### Fixes
 * removed a leftover debug print statement (see [#869](../../issues/869))
 * make sure tests work without HOME environment set (see [#870](../../issues/870))
 * automount drive or UNC path under Windows if needed for `pathlib.Path.mkdir()`
   (see [#890](../../issues/890))
+* adapt patching `io.open` to work with Python 3.12 (see [#836](../../issues/836))
 
 ## [Version 5.2.3](https://pypi.python.org/pypi/pyfakefs/5.2.3) (2023-08-18)
 Fixes a rare problem on pytest shutdown.

README.md

@@ -73,7 +73,7 @@ for more information about the limitations of pyfakefs.
 ### Continuous integration
 
 pyfakefs is currently automatically tested on Linux, macOS and Windows, with
-Python 3.7 to 3.11, and with PyPy3 on Linux, using
+Python 3.7 to 3.12, and with PyPy3 on Linux, using
 [GitHub Actions](https://github.com/pytest-dev/pyfakefs/actions).
 
 ### Running pyfakefs unit tests

pyfakefs/fake_filesystem_unittest.py

@@ -36,7 +36,6 @@
 to `:py:class`pyfakefs.fake_filesystem_unittest.TestCase`.
 """
 import _io  # type:ignore[import]
-import builtins
 import doctest
 import functools
 import genericpath
@@ -562,7 +561,6 @@ def __init__(
         # save the original open function for use in pytest plugin
         self.original_open = open
         self.patch_open_code = patch_open_code
-        self.fake_open: fake_open.FakeFileOpen
 
         if additional_skip_names is not None:
             skip_names = [
@@ -655,8 +653,8 @@ def _init_fake_module_classes(self) -> None:
             "io": fake_io.FakeIoModule,
             "pathlib": fake_pathlib.FakePathlibModule,
         }
-        if IS_PYPY:
-            # in PyPy io.open, the module is referenced as _io
+        if IS_PYPY or sys.version_info >= (3, 12):
+            # in PyPy and later cpython versions, the module is referenced as _io
             self._fake_module_classes["_io"] = fake_io.FakeIoModule
         if sys.platform == "win32":
             self._fake_module_classes["nt"] = fake_path.FakeNtModule
@@ -853,7 +851,6 @@ def _refresh(self) -> None:
 
         self.fs = fake_filesystem.FakeFilesystem(patcher=self, create_temp_dir=True)
         self.fs.patch_open_code = self.patch_open_code
-        self.fake_open = fake_open.FakeFileOpen(self.fs)
         for name in self._fake_module_classes:
             self.fake_modules[name] = self._fake_module_classes[name](self.fs)
             if hasattr(self.fake_modules[name], "skip_names"):
@@ -932,9 +929,6 @@ def patch_modules(self) -> None:
             for module, attr in modules:
                 if attr in self.unfaked_modules:
                     self._stubs.smart_set(module, name, self.unfaked_modules[attr])
-        if sys.version_info >= (3, 12):
-            # workaround for patching open - does not work with skip modules
-            self._stubs.smart_set(builtins, "open", self.fake_open)
 
     def patch_defaults(self) -> None:
         for fct, idx, ft in self.FS_DEFARGS:

pyfakefs/fake_io.py

@@ -95,9 +95,16 @@ def open(
         # specific modules; instead we check if the caller is a skipped
         # module (should work in most cases)
         stack = traceback.extract_stack(limit=2)
+        # handle the case that we try to call the original `open_code`
+        # and get here instead (since Python 3.12)
+        from_open_code = (
+            sys.version_info >= (3, 12)
+            and stack[0].name == "open_code"
+            and stack[0].line == "return self._io_module.open_code(path)"
+        )
         module_name = os.path.splitext(stack[0].filename)[0]
         module_name = module_name.replace(os.sep, ".")
-        if any(
+        if from_open_code or any(
             [
                 module_name == sn or module_name.endswith("." + sn)
                 for sn in self.skip_names

pyfakefs/tests/fake_filesystem_unittest_test.py

@@ -18,6 +18,7 @@
 Test the :py:class`pyfakefs.fake_filesystem_unittest.TestCase` base class.
 """
 import glob
+import importlib.util
 import io
 import multiprocessing
 import os
@@ -28,6 +29,8 @@
 import tempfile
 import unittest
 import warnings
+from contextlib import redirect_stdout
+from io import StringIO
 from pathlib import Path
 from unittest import TestCase, mock
 
@@ -228,14 +231,12 @@ def test_import_function_from_os_as_other_name(self):
         stat_result = pyfakefs.tests.import_as_example.file_stat2(file_path)
         self.assertEqual(3, stat_result.st_size)
 
-    @unittest.skipIf(sys.version_info >= (3, 12), "Currently not working in 3.12")
     def test_import_open_as_other_name(self):
         file_path = "/foo/bar"
         self.fs.create_file(file_path, contents=b"abc")
         contents = pyfakefs.tests.import_as_example.file_contents1(file_path)
         self.assertEqual("abc", contents)
 
-    @unittest.skipIf(sys.version_info >= (3, 12), "Currently not working in 3.12")
     def test_import_io_open_as_other_name(self):
         file_path = "/foo/bar"
         self.fs.create_file(file_path, contents=b"abc")
@@ -398,10 +399,6 @@ def test_fake_path_does_not_exist7(self):
         self.fs.create_file("foo")
         self.assertFalse(pyfakefs.tests.import_as_example.check_if_exists7("foo"))
 
-    @unittest.skipIf(
-        sys.version_info >= (3, 12),
-        "Skip modules currently not working for open in 3.12",
-    )
     def test_open_succeeds(self):
         pyfakefs.tests.import_as_example.open_this_file()
 
@@ -447,10 +444,6 @@ def test_fake_path_does_not_exist7(self):
         self.fs.create_file("foo")
         self.assertFalse(pyfakefs.tests.import_as_example.check_if_exists7("foo"))
 
-    @unittest.skipIf(
-        sys.version_info >= (3, 12),
-        "Skip modules currently not working for open in 3.12",
-    )
     def test_open_succeeds(self):
         pyfakefs.tests.import_as_example.open_this_file()
 
@@ -787,6 +780,7 @@ def load_configs(configs):
     return retval
 
 
+@unittest.skipIf(sys.version_info < (3, 8), "open_code new in Python 3.8")
 class AutoPatchOpenCodeTestCase(fake_filesystem_unittest.TestCase):
     """Test patching open_code in auto mode, see issue #554."""
 
@@ -806,6 +800,18 @@ def test_run_path(self):
     def test_run_module(self):
         load_configs([self.config_module])
 
+    def import_foo(self):
+        spec = importlib.util.spec_from_file_location("bar", "/foo/bar.py")
+        mod = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(mod)
+
+    @unittest.skipIf(sys.platform == "win32", "Not yet working under Windows")
+    def test_exec_module_in_fake_fs(self):
+        self.fs.create_file("/foo/bar.py", contents="print('hello')")
+        with redirect_stdout(StringIO()) as stdout:
+            self.import_foo()
+        assert stdout.getvalue() == "hello\n"
+
 
 class TestOtherFS(fake_filesystem_unittest.TestCase):
     def setUp(self):

setup.cfg

@@ -33,6 +33,7 @@ classifiers =
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
+    Programming Language :: Python :: 3.12
     Programming Language :: Python :: Implementation :: CPython
     Programming Language :: Python :: Implementation :: PyPy
     Operating System :: POSIX