Don't mock some os functions on windows

[vijayphoenix]

Fix #817

Related #1911 (comment)

[Eshan-Agarwal]

@vijayphoenix Can you check if it works properly now ?. It's still shows me same error after do modification as in this PR

Traceback (most recent call last):
File "c:\users\eshan\desktop\tf_tfds\datasets\tensorflow_datasets\testing\dataset_builder_testing.py", line 166, in setUp
self._mock_out_forbidden_os_functions()
File "c:\users\eshan\desktop\tf_tfds\datasets\tensorflow_datasets\testing\dataset_builder_testing.py", line 185, in _mock_out_forbidden_os_functions
getattr(mock_os, fop).side_effect = err
File "C:\Users\eshan\Anaconda3\envs\keras-gpu\lib\unittest\mock.py", line 585, in getattr
raise AttributeError("Mock object has no attribute %r" % name)
AttributeError: Mock object has no attribute 'chown'

[vijayphoenix]

I think you have not included the changes in the proper location file as your stack trace corresponds to the old file.

[Eshan-Agarwal]

@vijayphoenix earlier was my mistake I change in wrong files but still got same error after do proper changes

Traceback (most recent call last):
File "c:\users\eshan\desktop\tf_tfds\datasets\tensorflow_datasets\testing\dataset_builder_testing.py", line 166, in setUp
self._mock_out_forbidden_os_functions()
File "c:\users\eshan\desktop\tf_tfds\datasets\tensorflow_datasets\testing\dataset_builder_testing.py", line 185, in _mock_out_forbidden_os_functions
getattr(mock_os, fop).side_effect = err
File "C:\Users\eshan\Anaconda3\envs\keras-gpu\lib\unittest\mock.py", line 585, in getattr
raise AttributeError("Mock object has no attribute %r" % name)
AttributeError: Mock object has no attribute 'chown'

[vijayphoenix]

The stack trace is still the same (the line no. should change as the file was modified).

To avoid these types of problems, I suggest you make a new env.

[Eshan-Agarwal]

@vijayphoenix Yeah right actually I messed with some files its working great :-)

[Conchylicultor]

Thank you for fixing this.

Note internally, I've replaced this code by:

    for fop in FORBIDDEN_OS_FUNCTIONS:
      if os.name == "nt" and not hasattr(os, fop):
        continue  # Not all os functions are available on Windows.
      ...

It should be more generic, rather than hardcoding specific values. However I don't have access to windows machine so I can't really test this.

[vijayphoenix]

Tested; works on my machine.