os.path.isfile incorrect result for file without read permissions.

[jacobbogdanov]

Describe the bug
under pyfakefs os.path.isfile (and pathlib.Path.is_file) return False for a file without read permissions set, while the original implementation returns True.

How To Reproduce

import os
from typing import Iterator

import pytest
from pyfakefs import fake_filesystem


class TestRealFs:
    @pytest.fixture
    def unreadable_file(self, tmp_path) -> Iterator[str]:
        path = tmp_path / "foo"
        try:
            path.touch()
            path.chmod(0o000)
            yield str(path)
        finally:
            path.chmod(0o644)

    def test_exists(self, unreadable_file):
        assert os.path.exists(unreadable_file)

    def test_isfile(self, unreadable_file):
        assert os.path.isfile(unreadable_file)

    def test_not_exists(self):
        assert not os.path.exists("/does/not/exist")

    def test_not_isfile(self):
        assert not os.path.isfile("/does/not/exist")


class TestPyfakeFs:
    @pytest.fixture
    def unreadable_file(self, fs: fake_filesystem.FakeFilesystem) -> str:
        path = "/tmp/foo"
        fs.create_file(path, st_mode=0o000)
        return path

    def test_exists(self, unreadable_file):
        assert os.path.exists(unreadable_file)

    def test_isfile(self, unreadable_file):
        assert os.path.isfile(unreadable_file)  # this fails (and differs from TestRealFs::test_isfile)

    def test_not_exists(self, fs):
        assert not os.path.exists("/does/not/exist")

    def test_not_isfile(self, fs):
        assert not os.path.isfile("/does/not/exist")

$ py.test pyfakefs_test.py --randomly-dont-reorganize -vvv
====================================================== test session starts ======================================================
platform darwin -- Python 3.6.12, pytest-6.0.1, py-1.9.0, pluggy-0.13.1 -- /bin/python3.6
cachedir: .pytest_cache
Using --randomly-seed=1614180334
rootdir: /Users/jbogdanov/code/p2
plugins: timeout-1.3.4, mongodb-2.1.2, mock-3.1.0, randomly-3.1.0, requests-mock-1.7.0, stubprocess-0.1.0, pyfakefs-3.5.8, aiohttp-0.3.0, asyncio-0.12.0, lazy-fixture-0.6.3, cov-2.8.1
collected 8 items                                                                                                               

pyfakefs_test.py::TestRealFs::test_exists PASSED                                                                          [ 12%]
pyfakefs_test.py::TestRealFs::test_isfile PASSED                                                                          [ 25%]
pyfakefs_test.py::TestRealFs::test_not_exists PASSED                                                                      [ 37%]
pyfakefs_test.py::TestRealFs::test_not_isfile PASSED                                                                      [ 50%]
pyfakefs_test.py::TestPyfakeFs::test_exists PASSED                                                                        [ 62%]
pyfakefs_test.py::TestPyfakeFs::test_isfile FAILED                                                                        [ 75%]
pyfakefs_test.py::TestPyfakeFs::test_not_exists PASSED                                                                    [ 87%]
pyfakefs_test.py::TestPyfakeFs::test_not_isfile PASSED                                                                    [100%]

=========================================================== FAILURES ============================================================
___________________________________________________ TestPyfakeFs.test_isfile ____________________________________________________

self = <pyfakefs_test.TestPyfakeFs object at 0x10c4a8b38>, unreadable_file = '/tmp/foo'

    def test_isfile(self, unreadable_file):
>       assert os.path.isfile(unreadable_file)
E       AssertionError: assert False
E        +  where False = <bound method FakePathModule.isfile of <pyfakefs.fake_filesystem.FakePathModule object at 0x10c330c50>>('/tmp/foo')
E        +    where <bound method FakePathModule.isfile of <pyfakefs.fake_filesystem.FakePathModule object at 0x10c330c50>> = <pyfakefs.fake_filesystem.FakePathModule object at 0x10c330c50>.isfile
E        +      where <pyfakefs.fake_filesystem.FakePathModule object at 0x10c330c50> = os.path

pyfakefs_test.py:58: AssertionError
==================================================== short test summary info ====================================================
FAILED pyfakefs_test.py::TestPyfakeFs::test_isfile - AssertionError: assert False
================================================== 1 failed, 7 passed in 1.27s ==================================================

Your environment

Darwin-19.6.0-x86_64-i386-64bit
Python 3.6.12 (default, Dec  2 2020, 12:31:12) 
[GCC Apple LLVM 12.0.0 (clang-1200.0.32.27)]
pyfakefs 4.3.3

and

Linux-3.10.0-862.2.3.el7.x86_64-x86_64-with-centos-7.5.1804-Core
Python 3.6.6 (default, Aug 13 2018, 18:24:23) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)]
pyfakefs 3.3

[mrbean-bremen]

Thanks - I will have a look!

[mrbean-bremen]

Should be fixed now in master - please check!
Do you need a new release?

[jacobbogdanov]

Thanks for the speedy fix!

A new release would be awesome

[mrbean-bremen]

Ok, done.