Check if sys.stderr has isatty

[eggplants]

Closes: #1760

Proposed Changes:

• Check if sys.stderr has isatty in rdflib/__init__.py.

[aucampia]

Please include tests.

[aucampia]

Please include tests.

@eggplants Looking at the issue this is trying to I think I can accept this without tests, however tests always makes it an easier choice to approve.

I would like to see this code being removed though at some point in time, logging setup should be left to the user of the library, as with this approach it is likely that the setup is not as users want it, but I guess while it is there best to make it not break.

[aucampia]

Approving but will wait for at least one more review since there are no tests and will really appreciate some tests here to make sure we can actually reproduce the issue and ensure it is fixed.

[white-gecko]

Do I get it right, only in the case that sys.stderr has isatty() the logging is enabled?

[eggplants]

Do I get it right, only in the case that sys.stderr has isatty() the logging is enabled?

Yes.

[aucampia]

Test works fine even without the change, and as per our guide:

https://github.com/RDFLib/rdflib/blob/master/docs/developers.rst#tests

Tests that you add should show how your new feature or bug fix is doing what you say it is doing: if you remove your enhancement, your new tests should fail!

I will look at adding tests when I have time but it will be some weeks I think, as there are other things I think are higher priority.

[eggplants]

Is there a way to overwrite sys.stderr with None from the outside without changes to __init__.py? sys.stderr = None in the test seem to be reflected. Sorry for my stupidity.

[aucampia]

I think the best way to test it is to create a new python process with stdout closed, which will result in stdout being null as far as I understand, though I'm not entirely sure.

https://github.com/python/cpython/blob/d4a93e4de17ed8c2334fc72ca4cee737c3b738ec/Python/bltinmodule.c#L1871-L1873

        /* sys.stdout may be None when FILE* stdout isn't connected */
        if (file == Py_None)
            Py_RETURN_NONE;

[aucampia]

The other option is to use one of:

• https://docs.pytest.org/en/stable/how-to/monkeypatch.html
• https://docs.python.org/3/library/unittest.mock.html

[nicholascar]

Approving but can't merge until Drone is working again and all tests are seen to pass.

[aucampia]

Removed the test file as it is out of sync with master branch organization and it passes even without this PR, can be added in another PR if there is something else it tests for.

[aucampia]

CI passed now, again the test is removed as it passes with or without this change, I will merge tonight still if there are no objections. I think this change is safe enough.