Add disabled() method to capsys and capfd

[nicoddemus]

Wanted to get feedback if I should continue working on this.

Missing docs mostly

Fix #1599

[coveralls]

Coverage decreased (-0.05%) to 92.379% when pulling e179bc4 on nicoddemus:issue-1599-disable-cap-fixtures into b5bd4d9 on pytest-dev:features.

[coveralls]

Coverage decreased (-0.05%) to 92.379% when pulling 4a3d57f on nicoddemus:issue-1599-disable-cap-fixtures into 9232389 on pytest-dev:features.

[RonnyPfannschmidt]

Can you check it against xdist?

[The-Compiler]

I like this! It'd also make it easier to add an uncaptured pytest.print(msg) for easy printf-style debugging (without having to use -s and being greeted by a firehose of output).

[nicoddemus]

Nice idea on pytest.print... but I think this should be in a separate issue, specially to discuss UI/implementation.

[nicoddemus]

Can you check it against xdist?

Good thinking, will do it later.

[nicoddemus]

Testing with xdist everything seems to work:

import pytest

@pytest.mark.parametrize('i', list(range(100)))
def test(i, capsys):
    with capsys.disabled():
        print(i, 'hey')

$ py.test -n3
============================= test session starts =============================
platform win32 -- Python 3.5.0, pytest-2.10.0.dev1, py-1.4.31, pluggy-0.3.1
rootdir: X:\pytest, inifile: tox.ini
plugins: hypothesis-3.1.0, xdist-1.14
gw0 [100] / gw1 [100] / gw2 [100]
scheduling tests via LoadScheduling
....................................................................................................
========================= 100 passed in 1.72 seconds ==========================

The output does not show, but neither does it show if you pass -s; that's a general problem currently known with pytest-xdist, unfortunately.

[nicoddemus]

Added CHANGELOG and documentation, I think the PR is ready for a final review. 😁

[coveralls]

Coverage decreased (-0.05%) to 92.378% when pulling 72bf11c on nicoddemus:issue-1599-disable-cap-fixtures into 308396a on pytest-dev:features.