Call os.makedirs('', exist_ok=True) will not raise FileNotFoundError in fakefs

[vuryleo]

Describe the bug
os.makedirs('', exist_ok=True) will not raise FileNotFoundError

How To Reproduce

import os

from pyfakefs.fake_filesystem_unittest import Patcher

with Patcher():
    print('fakefs')
    os.makedirs('', exist_ok=True)

print('os')
os.makedirs('', exist_ok=True)

Output:

fakefs
os
Traceback (most recent call last):
  File "[redacted].py", line 10, in <module>
    os.makedirs('', exist_ok=True)
  File "/usr/lib/python3.6/os.py", line 220, in makedirs
    mkdir(name, mode)
FileNotFoundError: [Errno 2] No such file or directory: ''

Your enviroment
Please run the following and paste the output.

Linux-4.15.0-55.60-x86_64-with-Ubuntu-18.04-bionic
Python 3.6.8 (default, Oct  7 2019, 12:59:55) 
[GCC 8.3.0]
pyfakefs 3.7.1

[mrbean-bremen]

Ok, thanks - strange use case, I didn't know that it behaves that way. Will have a look tonight...

[vuryleo]

The use case is that we wanna implement something like shutil.move. So we need to makedirs(dirname(dst), exist_ok=True) first.

Then we encountered that dirname('local_file') == ''. Boom.

At last we wish to add this case to our unit test, and discovered that pyfakefs does not complain about this.

[mrbean-bremen]

Ok, thanks - I still find the behavior a bit unexpected, and it seems not to be documented. Anyway, I will have a look later.

[mrbean-bremen]

Turned out mkdir has the same behavior, and that was already implemented - so not so unexpected in the end, I guess...