os.access() is not properly faked, wrong signature since python3.3

[ArminGruner]

Describe the bug
Signature of os.access() (since Python3.3) is:

os.access = access(path, mode, *, dir_fd=None, effective_ids=False, follow_symlinks=True)

If some code uses the "effective_ids" feature, it does not work when using pyfakefs because the "os.access" function in fake_filesystem.py::FakeOsModule::access() does not match the signature:

def access(self, path, mode, *, dir_fd=None, follow_symlinks=True):

How To Reproduce

import os

def test_fakefs(fs):
    file_path = '/test/file.txt'
    assert not os.access(file_path, os.R_OK)
    fs.create_file(file_path)
    assert os.access(file_path, os.R_OK)

def test_fakefs_effective_ids(fs):
    file_path = '/test/file.txt'
    assert not os.access(file_path, os.R_OK, effective_ids=True)
    fs.create_file(file_path)
    assert os.access(file_path, os.R_OK, effective_ids=True)

» pytest test_os_access.py

```» pytest test_os_access.py
===================================== test session starts =====================================
platform freebsd12 -- Python 3.7.9, pytest-5.4.3, py-1.9.0, pluggy-0.13.1
rootdir: /usr/home/armin/git-repos/link-m/py-linkm, inifile: tox.ini
plugins: mongo-2.0.0, mock-3.5.1, Faker-5.6.1, faker-2.0.0, pyfakefs-4.3.3
collected 2 items                                                                             

test_os_access.py .F                                                                    [100%]

========================================== FAILURES ===========================================
__________________________________ test_fakefs_effective_ids __________________________________

fs = <pyfakefs.fake_filesystem.FakeFilesystem object at 0x803f6ce10>

    def test_fakefs_effective_ids(fs):
        file_path = '/test/file.txt'
>       assert not os.access(file_path, os.R_OK, effective_ids=True)
E       TypeError: access() got an unexpected keyword argument 'effective_ids'

/usr/home/armin/git-repos/link-m/py-linkm/test_os_access.py:11: TypeError
=================================== short test summary info ===================================
FAILED test_os_access.py::test_fakefs_effective_ids - TypeError: access() got an unexpected ...
================================= 1 failed, 1 passed in 1.05s =================================

Your environment
Please run the following and paste the output.

python -c "import platform; print(platform.platform())"
python -c "import sys; print('Python', sys.version)"
python -c "from pyfakefs.fake_filesystem import __version__; print('pyfakefs', __version__)"

FreeBSD-12.1-RELEASE-p10-amd64-64bit-ELF
Python 3.7.9 (default, Dec 3 2020, 01:19:24)
[Clang 8.0.1 (tags/RELEASE_801/final 366581)]
pyfakefs 4.3.3

[mrbean-bremen]

Good point. I'll probably just add the argument for now, without it having an effect, as we don't really support guid/uid permissions (apart from uid 0 being root). Do you need to have it any functionality?

[ArminGruner]

Hi, thanks for the instant reply.

I think it's fine to just accept the argument, but not switching test behaviour!

I was just discovering the mismatch when testing a function decorated with pidfile from the pid python package (https://github.com/trbs/pid/). It uses os.access() under the umbrella, and unfortunately uses the named effective_ids argument.

[mrbean-bremen]

Ok, thanks - will do this in this case in a moment.

[mrbean-bremen]

Should work now in master.

[ArminGruner]

Thanks for the fix! I confirm that using master from github works for me now!

[mrbean-bremen]

Can you live with master, or do you need a patch release?

[ArminGruner]

Hi, thanks for asking!
I'm fine waiting for any release train.
I've pinned the commit hash in my tox.ini ;-)