Support pathlib.Path parameter in create_dir()

[shuttle1987]

I created a repository here to show the bug I am getting:
https://github.com/shuttle1987/pyfakefs-pathlib-fail

Essentially when this test is run:

def test_pathlib(fs): #fs is the fake filesystem fixture
    """Attempt to use a pathlib path"""

    import pathlib
    base_dir = pathlib.Path('/tmp/corpus_data')
    fs.create_dir(base_dir)

    from example_lib.searcher import determine_labels

The failure is as follows:

$ python -m pytest
================================================ test session starts ================================================
platform linux -- Python 3.5.2, pytest-3.6.0, py-1.5.3, pluggy-0.6.0
rootdir: /home/janis/pyfakefs-pathlib-fail, inifile:
plugins: cov-2.5.1, pyfakefs-3.4.1
collected 1 item                                                                                                    

tests/test_example.py F                                                                                       [100%]

===================================================== FAILURES ======================================================
___________________________________________________ test_pathlib ____________________________________________________

fs = <pyfakefs.fake_filesystem.FakeFilesystem object at 0x7f03fc2b9a90>

>   ???

home/janis/pyfakefs-pathlib-fail/tests/test_example.py:6: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
home/janis/pyfakefs-pathlib-fail/venv/lib/python3.5/site-packages/pyfakefs/fake_filesystem.py:2137: in create_dir
    ???
home/janis/pyfakefs-pathlib-fail/venv/lib/python3.5/site-packages/pyfakefs/fake_filesystem.py:1362: in absnormpath
    ???
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <pyfakefs.fake_filesystem.FakeFilesystem object at 0x7f03fc2b9a90>, file_path = PosixPath('/tmp/corpus_data')

>   ???
E   AttributeError: 'PosixPath' object has no attribute 'startswith'

home/janis/pyfakefs-pathlib-fail/venv/lib/python3.5/site-packages/pyfakefs/fake_filesystem.py:1578: AttributeError
============================================= 1 failed in 0.12 seconds ==============================================

As far as I can tell from reading the documentation this library is supposed to patch pathlib.Path.

[mrbean-bremen]

Thanks for the report! Currently, create_dir is not designed to take a Path parameter, so you have to convert it to a string first, e.g. fs.create_dir (str (base_dir)).
But I agree that it would make sense to support this - I will adapt it accordingly.

[shuttle1987]

I have converted to a str as requested but there's still an issue with the paths, consider this test case:

def test_determine_labels(fs): #fs is the fake filesystem fixture
    """test the function that determines what labels exist in a directory"""
    from pyfakefs.fake_filesystem_unittest import Patcher

    with Patcher(use_dynamic_patch=True) as patcher:
        import pathlib
    base_dir = pathlib.Path('/tmp/corpus_data')
    label_dir = base_dir / "label"
    fs.create_dir(str(base_dir))
    fs.create_dir(str(label_dir))
    test_1_phonemes = 'ɖ ɯ ɕ i k v̩'
    test_1_phonemes_and_tones = 'ɖ ɯ ˧ ɕ i ˧ k v̩ ˧˥'
    test_2_phonemes = 'g v̩ tsʰ i g v̩ k v̩'
    test_2_phonemes_and_tones = 'g v̩ ˧ tsʰ i ˩ g v̩ ˩ k v̩ ˩'
    fs.create_file(str(label_dir / "test1.phonemes"), contents=test_1_phonemes)
    fs.create_file(str(label_dir / "test1.phonemes_and_tones"), contents=test_1_phonemes_and_tones)
    fs.create_file(str(label_dir / "test2.phonemes"), contents=test_2_phonemes)
    fs.create_file(str(label_dir / "test2.phonemes_and_tones"), contents=test_1_phonemes_and_tones)
    assert base_dir.exists()
    assert label_dir.exists()

This fails with the following:

_________________________________ test_determine_labels _________________________________

fs = <pyfakefs.fake_filesystem.FakeFilesystem object at 0x7f3706e3ff28>

>   ???
E   AssertionError: assert False
E    +  where False = <bound method Path.exists of PosixPath('/tmp/corpus_data')>()
E    +    where <bound method Path.exists of PosixPath('/tmp/corpus_data')> = PosixPath('/tmp/corpus_data').exists

home/janis/persephone/persephone/tests/test_corpus.py:42: AssertionError

Also I notice the stacktrace is not quite right here either with the > ???

Does this imply that pathlib operations can't be relied upon?

[shuttle1987]

Is the stacktrace issue related to #381?

[mrbean-bremen]

Is the stacktrace issue related to #381?

Exactly. This should be fixed in master for Python 3.
I will have a look at the other issue in the evening or the weekend.

[mrbean-bremen]

The following works fine for me:

# -*- coding: utf-8 -*-
import pathlib


def test_determine_labels(fs):
    base_dir = pathlib.Path('/tmp/corpus_data')
    label_dir = base_dir / "label"
    fs.create_dir(str(base_dir))
    fs.create_dir(str(label_dir))
    test_1_phonemes = 'ɖ ɯ ɕ i k v̩'
    fs.create_file(str(label_dir / "test1.phonemes"),
                   contents=test_1_phonemes, encoding='utf-8')
    assert base_dir.exists()
    assert label_dir.exists()

Note that I had to add the utf-8 stuff because I tested this under Windows, where UTF-8 is not the default encoding - under Linux it should not be needed (though it would make the code more compatible).
The relevent change is the pathlib import - the import inside the additional patcher context does not work and is not needed. The fs fixture already has a patcher instantiated that takes care of the patching, so the additional patcher tries to patch it again, and removes the patching after going out of context.

[shuttle1987]

Thanks for the patch!