pyfakefs

Follow-up bugfix release for release 6.1.5.

Fixes a Windows-specific issue with os.path.realpath.

Fixes an incompatibility with the VCCode unittest runner.

Minor bugfix release.

Fixes

• handle expanduser() and home() correctly in cross OS usage (see #1289)

Fixes a regression caused by the introduced weak references.

• fixes a packaging issue in latest version

• changes back-link references to weak references
• minor bugfixes
• see the release notes for a list of changes

• removes some deprecated functionality
• removes support for Python < 3.10
• see the release notes for a list of changes

• fixes a problem with pathlib.glob in Python 3.14

Fixes a regression introduced in version 5.9.0.

Fixes

• fixed a deadlock in shutil.copytree if copying using an shutil function as copy_function argument (see #1235)

Adds official support for Python 3.14. Last minor version before the 6.0 release.

Changes

• the errno codes set in OSError have changed for some specific error conditions in Windows 11/Windows Server 2025; pyfakefs now matches this behavior instead of the previous behavior under Windows 10
• added official support for Python 3.14

Enhancements

• added support for os.readinto in Python 3.14
• added support for pathlib.copy and pathlib.copy_into in Python 3.14

Fixes

• fixes patching of Debian-specific tempfile in Python 3.13 ( see #1214)

Fixes a utility method.

Changes

• a warning is now issued if trying to create a nested fake filesystem with custom arguments (custom arguments are ignored in this case, as the existing fake filesystem is used)

Fixes

• fixed fake_filesystem.add_package_metadata that had never worked correctly (see #1205)

Infrastructure

• updated the package build-system minimum version to setuptools v61.2 and higher

Fixes interaction with pytest.

Fixes

• fixed an interaction problem of fs with other pytest fixtures ( see #1200)

Infrastructure

• fixed some warnings in tests (see #1190)

Fixes regression in packaging in version 5.9.0.

Fixes

• fixed handling of added strict argument in Python 3.9.23
• make sure test files are packaged (see #1186)

Adds support for an API change in latest Python patch releases.

Changes

• the message from an OSError raised in the fake filesystem has no longer the postfix "in the fake filesystem" (see #1159)
• changed implementation of FakeShutilModule to prepare it for usage without the patcher (see #1171)

Enhancements

• added convenience function add_package_metadata to add the metadata of a given package to the fake filesystem (see #1155)

Fixes

• fixed handling of dynamic imports from code in the fake filesystem in Python > 3.11 (see #1121)
• fixed workaround for recursion with pytest under Windows to ignore capitalization of pytest executable (see #1096)
• added missing mode property to fake file wrapper (see #1162)
• fixed instantiation of a standalone FakePathlibModule for Python >= 3.11 (see #1169)
• added support for new value "ALLOW_MISSING" of strict argument in os.path.realpath (introduced in latest patch version of Python >= 3.10, see #1180)

Infrastructure

• adapt test for increased default buffer size in Python 3.14a6
• replace session-scoped with module-scoped fixture in test, run pytest over all tests in docker containers (see #1151)
• remove setup.py and setup.cfg in favor of pyproject.toml

Adds preliminary support for Python 3.14.

Changes

• added some preliminary support for Python 3.14
• change behavior of FakeFilesystem.get_object() to ignore permissions as it has been before version 5.4.0 (see #1122)

Fixes

• fixed a problem with flushing if writing over the buffer end (see #1120)
• fixed a regression that could break tests under Posix in Python 3.12 (see #1126)
• fixed behavior for os.access for symlinks under Windows
• fixed permission problem on querying file properties (see #1122)
• fixed patching in pytest setup phase for module and session-scoped fs fixtures (see #1126)

Documentation

• use a theme for documentation supporting dark mode

Minor bugfix release.

Fixes

• fixed a problem with module and session scoped fixtures in Python 3.13 (see #1101)
• fixed handling of cwd if set to a pathlib.Path (see #1108)
• fixed documentation for cleanup handlers, added convenience handler reload_cleanup_handler (see #1105)

Fixes a regression in version 5.7.3.

Fixes

• fixed a regression in version 5.7.2 that tempfile was not patched after pause/resume (POSIX only, see #1098)
• added workaround for a recursion occurring if using pytest under Windows and Python >= 3.12 (see #1096)

Infrastructure

• run pytest-specific tests for all supported Python versions
• pytest is only supported for versions >= 6.2.5, earlier version do not work in Python >= 3.10 due to a pytest issue - adapted tests and documentation

Fixes some problems with patching.

Fixes

• added some support for loading fake modules in AUTO patch mode using importlib.import_module (see #1079)
• added some support to avoid patching debugger related modules (see #1083)

Performance

• avoid reloading tempfile in Posix systems

Infrastructure

• use trusted publisher for release (see https://docs.pypi.org/trusted-publishers/)

Fixes a regression in version 5.7.0 that broke patching fcntl.

Fixes

• fixes a regression that caused unfaked fcntl calls to fail ( see #1074)

Adds official Python 3.13 support, improves OS emulation behavior.

Changes

• officially support Python 3.13

Enhancements

• the additional_skip_names parameter now works with more modules ( see #1023)
• added support for os.fchmod, allow file descriptor argument for os.chmod only for POSIX for Python < 3.13

Performance

• avoid reloading glob in Python 3.13

Fixes

• removing files while iterating over scandir results is now possible ( see #1051)
• fake pathlib.PosixPath and pathlib.WindowsPath now behave more like in the real filesystem (see #1053)
• PurePosixPath reported Windows reserved names as reserved in Python >= 3.12 (see #1067)
• PurePosixPath.joinpath() incorrectly handled paths with drives under Windows in Python >= 3.12 (see #1070)

Adds preliminary Python 3.13 support.

Enhancements

• added preliminary support for Python 3.13 (tested with beta2) ( see #1017)
• added apply_umask argument to FakeFilesystem.create_dir to allow ignoring the umask ( see #1038)

Fixes

• use real open calls for remaining pathlib functions so that it works nice with skippedmodules ( see #1012)

Infrastructure

• Add pyupgrade as a pre-commit hook.

Deprecates the usage of pathlib2 and scandir.

Changes

• The usage of the pathlib2 and scandir modules in pyfakefs is now deprecated. They will now cause deprecation warnings if still used. Support for patching these modules will be removed in pyfakefs 6.0.
• PureWindowsPath and PurePosixPath now use filesystem-independent path separators, and their path-parsing behaviors are now consistent regardless of runtime platform and/or faked filesystem customization (see #1006).

Fixes

• fixed handling of Windows pathlib paths under POSIX and vice verse ( see #1006)
• correctly use real open calls in pathlib for skipped modules ( see #1012)

Fixes a regression.

Fixes

• fixed a regression from version 5.4.0 that incorrectly handled files opened twice via file descriptor (see #997)

Improves permission handling.

Changes

• the handling of file permissions under Posix should now mostly match the behavior of the real filesystem, which may change the behavior of some tests
• removed the argument module_cleanup_mode, that was introduced as a temporary workaround in the previous version - related problems shall be handled using a cleanup handler

Enhancements

• added support for O_NOFOLLOW and O_DIRECTORY flags in os.open (see #972 and #974)
• added support for fake os.dup, os.dup2 and os.lseek ( see #970)

Fixes

• fixed a specific problem on reloading a pandas-related module ( see #947), added possibility for unload hooks for specific modules
• use this also to reload django views (see #932)
• fixed EncodingWarning for Python >= 3.11 (see #957)
• consider directory ownership while adding or removing directory entries (see #959)
• fixed handling of directory enumeration and search permissions under Posix systems (see #960)
• fixed creation of the temp directory in the fake file system after a filesystem reset (see #965)
• fixed handling of dirfd in os.symlink (see #968)
• add missing follow_symlink argument to os.link (see #973)
• fixed handling of missing attribute in os.getxattr (see #971)
• fixed permission problem with shutil.rmtree if emulating Windows under POSIX (see #979)
• fixed handling of errors on opening files via file descriptor ( see #967)
• fixed handling of umask - it is now applied by default
• fixed behavior of os.makedirs (see #987)

Infrastructure

• replace undefined by own minimal implementation to avoid importing it (see #981)

Fixes a regression.

Fixes

• Fixed a regression due to the changed behavior of the dynamic patcher cleanup ( see #939). The change is now by default only made if the django module is loaded, and the behavior can be changed using the new argument module_cleanup_mode.

Packaging

• included tox.ini and a few more files into the source distribution ( see #937)

Bugfix release.

Fixes

• fixed handling of unhashable modules which cannot be cached ( see #923)
• reload modules loaded by the dynamic patcher instead of removing them - sometimes they may not be reloaded automatically (see #932)
• added back argument use_dynamic_patch as a fallback for similar problems

Bugfix release.

Fixes

• fixed a problem with patching _io under Python 3.12 (see #910)
• fixed a problem with accessing the temp path if emulating Linux under Windows (see #912)
• fixed result of os.walk with a path-like top directory (see #915)
• properly fixed the problem that filesystem patching was still active in the pytest logreport phase (see #904), the previous fix was incomplete

Mostly a bugfix release.

Changes

• changed behavior of add_real_directory to be able to map a real directory to an existing directory in the fake filesystem (see #901)

Fixes

• fixed the problem that filesystem patching was still active in the pytest logreport phase (see #904)
• restored compatibility with PyTorch 2.0 and above, as well as with other classes that have custom setattr methods (see #905)

Adds official support for Python 3.12.

Changes

• added official support for Python 3.12

Fixes

• removed a leftover debug print statement (see #869)
• make sure tests work without HOME environment set (see #870)
• automount drive or UNC path under Windows if needed for pathlib.Path.mkdir() (see #890)
• adapted patching io.open and io.open_code to work with Python 3.12 (see #836 and #892)

Fixes a rare problem on pytest shutdown.

Fixes

• Clear the patched module cache on session shutdown (pytest only) (see #866). Added a class method Patcher.clear_fs_cache for clearing the patched module cache.

Adds compatibility with PyPy 3.10 and Python 3.12.

Fixes

• Re-create temp directory if it had been created before on resetting file system (see #814).
• Excluded pytest pathlib modules from patching to avoid mixup of patched/unpatched code (see #814).
• Adapted to changes in Python 3.12 beta1 (only working partially, see #830 and #831).
• Adapted to changes in shutil in Python 3.12 beta2 (see #814).
• Fixed support for newer PyPi versions (see #859).

Documentation

• Added a note regarding the incompatibility of the built-in sqlite3 module with pyfakefs (see #850)

Infrastructure

• Added pytype check for non-test modules in CI (see #599).
• Added tests for different pypy3 versions.
• Added codespell hook to pre-commit

Fixes a regression in 5.2.0

Changes

• Made the user and group IDs accessible via dedicated get_uid and get_gid functions (for symmetry to set_uid / set_gid)

Fixes

• The test fixture is now included in the source distribution and installed with the package.
• Some public constants in fake_filesystem that had been moved to helpers are made accessible from there again (see #809).
• Add missing fake implementations for os.getuid and os.getgid (Posix only)
• Make sure a /tmp path exists under linux (TMPDIR may point elsewhere) (see #810)

Support for latest Python 3.12 version.

Changes

• Adapted fake pathlib to changes in Python 3.12a7 (last alpha version)

Fixes

• Properties defining the capabilities of some os functions like os.supports_follow_symlinks are now properly faked to contain the fake functions if the real functions are faked (see #799)

Supports current Python 3.12 version (alpha 6). We plan to make patch releases in case of breaking changes in alpha or beta versions.

Changes

• Fake module classes previously defined in fake_filesystem have now moved to their own modules: fake_os.FakeOsModule, fake_path.FakePathModule, fake_io.FakeIoModule and fake_open.FakeFileOpen. Additionally, all fake file classes have been moved to fake_file. While most of the changes shall be upwards compatible, we cannot exclude that we missed some problems.
• Under macOS, at test start a symlink /tmp to the actual temporary directory is now created in the fake filesystem.
• Patching of parsers for pandas >= 1.2 is removed since pandas now uses Python fs functions internally even when the engine selected is "c".

Features

• added possibility to set a path inaccessible under Windows by using chown() with the force_unix_mode flag (see #720)
• added support for current Python 3.12 version (alpha 6)
• added support for os.path.splitroot (new in Python 3.12)

New version before Debian freeze

Features

• added class level setup method setUpClassPyfakefs for unittest and class-scoped fixture fs_class for pytest (see #752)
• added experimental support for Python 3.12: added fake APIs for Windows junction support. These are not implemented and always return False.

Infrastructure

• replaced end-of-life CentOS with RedHat UBI9 docker image
• added tests for pytest 7.2.0
• added black to pre-commit checks, which caused some changes to the coding style (max line length is now 88, always use double quotes)
• added Python 3.12 to the test suite.
• migrated to setuptools declarative syntax.
• fixed docker tests when running on branches containing forward slashes

New version after the transfer to pytest-dev.

Changes

• the old-style API deprecated since version 3.4 has now been removed
• the method copyRealFile deprecated since version 3.2 has been removed - use add_real_file instead

Infrastructure

• transferred the repository to the pytest-dev organization
• renamed the master branch to main
• added automatic PyPI release workflow
• move documentation from GitHub Pages to Read the Docs

New Features

• added some support for st_blocks in stat result (see #722)

Fixes

• fixed handling of O_TMPFILE in os.open (caused handling of O_DIRECTORY as O_TMPFILE) (see #723)
• fixed handling of read permissions (see #719)

Changed handling of nested fixtures and bug fixes.

Changes

• fs fixtures cannot be nested; any nested fs fixture (for example inside an fs_session or fs_module fixture) will just reference the outer fixture (the behavior had been unexpected before)

Fixes

• reverted a performance optimization introduced in version 3.3.0 that caused hanging tests with installed torch (see #693)
• do not use the built-in opener in pathlib as it may cause problems (see #697)
• add support for path-like objects in shutil.disk_usage (see #699)
• do not advertise support for Python 3.6 in setup.py (see #707)
• return the expected type from fcntl.ioctl and fcntl.fcntl calls if arg is of type byte; the call itself does nothing as before
• do not skip filesystem modules by name to allow using own modules with the same name (see #707)
• add missing support for os.renames (see #714)

Another patch release that fixes a regression in version 4.6.

Changes

• automatically reset filesystem on changing is_windows_fs or is_macos (see #692) - ensures better upwards compatibility in most cases

  :warning: Make sure you write to the filesystem after you change is_windows_fs or is_macos, otherwise the changes will be lost.

Fixes

• fixed regression: os.path.exists returned True for any root drive path under Windows

Patch release that fixes an error in the previous patch.

Fixes

• fixed support for opener introduced in previous patch release (see #689)

Fixes incompatibility with Python 3.11 beta 4.

Note: Python 3.11 is only supported in the current beta 4 version, problems with later beta or rc versions are still possible. We will try to fix such problems in short order should they appear.

Fixes

• added support for opener argument in open, which is used in tempfile in Python 3.11 since beta 4 (see #686)

Infrastructure

• make sure tests run without pyfakefs installed as a package (see #687)

Adds support for Python 3.11, removes support for Python 3.6, changes root path behavior under Windows.

Changes

• Python 3.6 has reached its end of life on 2021/12/23 and is no longer officially supported by pyfakefs
  • os.stat_float_times has been removed in Python 3.7 and is therefore no longer supported
• under Windows, the root path is now effectively C:\ instead of \; a path starting with \ points to the current drive as in the real file system (see #673)
• fake pathlib.Path.owner() and pathlib.Path.group() now behave like the real methods - they look up the real user/group name for the user/group id that is associated with the fake file (see #678)

New Features

• added some support for the upcoming Python version 3.11 (see #677)
• added convenience fixtures for module- and session based fs fixtures (fs_module and fs_session)

Fixes

• fixed an incompatibility of tmpdir (and probably other fixtures) with the module-scoped version of fs; had been introduced in pyfakefs 4.5.5 by the fix for #666 (see #684)

Fixes a regression which broke tests with older pytest versions (< 3.9).

Changes

• minimum supported pytest version is now 3.0 (older versions do not work properly with current Python versions)

Fixes

• only skip _pytest.pathlib in pytest versions where it is actually present (see #669)

Infrastructure

• add tests with different pytest versions, starting with 3.0

Bugfix release, needed for compatibility with pytest 7.0.

Fixes

• correctly handle file system space for files opened in write mode (see #660)
• correctly handle reading/writing pipes via file (see #661)
• disallow encoding argument on binary open() (see #664)
• fixed compatibility issue with pytest 7.0.0 (see #666)

Minor bugfix release.

Fixes

• added missing mocked functions for fake pipe (see #650)
• fixed some bytes warnings (see #651)

Reverts a change in the previous release that could cause a regression.

Changes

• os.listdir, os.scandir and pathlib.Path.listdir now return the directory list in a random order only if explicitly configured in the file system (use fs.shuffle_listdir_results = True with fs being the file system). In a future version, the default may be changed to better reflect the real filesystem behavior (see #647)

This is a bugfix release.

Changes

• os.listdir, os.scandir and pathlib.Path.listdir now return the directory list in a random order (see #638)
• the fcntl module under Unix is now mocked, e.g. all functions have no effect (this may be changed in the future if needed, see #645)

Fixes

• fixed handling of alternative path separator in os.path.split, os.path.splitdrive and glob.glob (see #632)
• fixed handling of failed rename due to permission error (see #643)

This is a bugfix release.

Fixes

• added handling of path-like where missing
• improved handling of str/bytes paths
• suppress all warnings while inspecting loaded modules (see #614)
• do not import pandas and related modules if it is not patched (see #627)
• handle pathlib.Path.owner() and pathlib.Path.group by returning the current user/group name (see #629)
• fixed handling of use_known_patches=False (could cause an exception)
• removed Python 3.5 from metadata to disable installation for that version (see #615)

Infrastructure

• added test dependency check (see #608)
• skip tests failing with ASCII locale (see #623)

Adds some support for Python 3.10 and basic type checking.

Note: This version has been yanked from PyPI as it erroneously allowed installation under Python 3.5.

New Features

• added support for some Python 3.10 features:
  • new method pathlib.Path.hardlink_to
  • new newline argument in pathlib.Path.write_text
  • new follow_symlinks argument in pathlib.Path.stat and pathlib.Path.chmod
  • new 'strict' argument in os.path.realpath

Changes

• Python 3.5 has reached its end of life in September 2020 and is no longer supported
• pathlib2 is still supported, but considered to have the same functionality as pathlib and is no longer tested separately; the previous behavior broke newer pathlib features if pathlib2 was installed (see #592)

Fixes

• correctly handle byte paths in os.path.exists (see #595)
• Update fake_pathlib to support changes coming in Python 3.10 (see
• correctly handle UNC paths in os.path.split and in directory path evaluation (see #606)

Infrastructure

• added mypy checks in CI (see #599)

Adds better support for Python 3.8 / 3.9.

New Features

• added support for pathlib.Path.link_to (new in Python 3.8) (see #580)
• added support for pathlib.Path.readlink (new in Python 3.9) (see #584)
• added FakeFilesystem.create_link convenience method which creates intermittent directories (see #580)

Fixes

• fixed handling of pipe descriptors in the fake filesystem (see #581)
• added non-functional argument effective_ids to os.access (see #585)
• correctly handle os.file for unreadable files (see #588)

Infrastructure

• added automatic documentation build and check-in

Another bugfix release.

Fixes

• Reverted one Windows-specific optimization that can break tests under some conditions (see #573)
• Setting os did not reset os.sep and related variables, fixed null device name, added os.pathsep and missing os.path variables (see #572)

This is a bugfix release that fixes a regression introduced in version 4.2.0.

Fixes

• open calls had not been patched for modules with a name ending with "io" (see #569)

This is an update to the performance release, with more setup caching and the possibility to disable it.

Changes

• Added caching of patched modules to avoid lookup overhead
• Added use_cache option and clear_cache method to be able to deal with unwanted side effects of the newly introduced caching

Infrastructure

• Moved CI builds to GitHub Actions for performance reasons

This is mostly a performance release. The performance of the pyfakefs setup has been decreasing sufficiently, especially with the 4.x releases. This release corrects that by making the most expansive feature optional, and by adding some other performance improvements. This shall decrease the setup time by about a factor of 20, and it shall now be comparable to the performance of the 3.4 release.

Changes

• The patchfs decorator now expects a positional argument instead of the keyword arguments fs. This avoids confusion with the pytest fs fixture and conforms to the behavior of mock.patch. You may have to adapt the argument order if you use the patchfs and mock.patch decorators together (see #566)
• Default arguments that are file system functions are now not patched by default to avoid a large performance impact. An additional parameter patch_default_args has been added that switches this behavior on (see #567).

Performance

• Added performance improvements in the test setup, including caching the unpatched modules

This is a bugfix release that fixes a regression issue.

Fixes

• remove dependency of pyfakefs on pytest (regression, see #565)

New Features

• add support for the buffering parameter in open (see #549)
• add possibility to patch io.open_code using the new argument patch_open_code (since Python 3.8) (see #554)
• add possibility to set file system OS via FakeFilesystem.os

Fixes

• fix check for link in os.walk (see #559)
• fix handling of real files in combination with home if simulating Posix under Windows (see #558)
• do not call fake open if called from skipped module (see #552)
• do not call fake pathlib.Path if called from skipped module (see #553)
• fixed handling of additional_skip_names with several module components
• allow to open existing pipe file descriptor (see #493)
• do not truncate file on failed flush (see #548)
• suppress deprecation warnings while collecting modules (see #542)
• add support for os.truncate and os.ftruncate (see #545)

Infrastructure

• fixed another problem with CI test scripts not always propagating errors
• make sure pytest will work without pyfakefs installed (see #550)

New Features

• Added some support for pandas (read_csv, read_excel and more), and for django file locks to work with the fake filesystem (see #531)

Fixes

• os.expanduser now works with a bytes path
• Do not override global warnings setting in Deprecator (see #526)
• Make sure filesystem modules in pathlib are patched (see #527)
• Make sure that alternative path separators are correctly handled under Windows (see #530)

Infrastructure

• Make sure all temporary files from real fs tests are removed

This as a patch release that only builds for Python 3. Note that versions 4.0.0 and 4.0.1 will be removed from PyPI to disable installing them under Python 2.

Fixes

• Do not build for Python 2 (see #524)