`CliRunner` does not capture `logging` output on `stdout`

[blueyed]

Is this expected?

It feels like a missing feature, so I'd be happy to provide it giving some pointers.

My test:

def test_cli_run_with_args(runner):
    result = runner.invoke(cli.main, ['run', 'printf', '%s', '--'])
    …

And in the run command I have:

logger.warn('The temporary profile file (%s) has not been created.',
            profile_file_name)

Where logger is logger = logging.getLogger('covimerage'), which gets setup in __init__.py:

logger = logging.getLogger('covimerage')
logger.setLevel(logging.INFO)
logger.addHandler(logging.StreamHandler(sys.stdout))

When run manually the warning shows up.

It also shows up in pytest's Captured stdout call.

[blueyed]

That is more a problem of logging using not sys.stdout / sys.stderr directly, but where it pointed at when the handler gets created, and is therefore kind of expected.

As for me, I am using a handler based on logging's own _StderrHandler that will use sys.stderr always.

[kdeldycke]

This is going to be addressed in v8.4.0 by #3391 which introduce a new capture="fd" mode to CliRunner.