capfd not working in 3.3.1

Fixtures that use capfd don’t seem to work in version 3.3.1 running on Ubuntu 14.04 LTS with anaconda 3.6.3

import sys

@pytest.fixture()
def fix(capfd):
    yield None
    out, err = capfd.readouterr()
    stdout_filename = "/tmp/stdout"
    stderr_filename = "/tmp/stderr"
    mode = 'w'
    with open(stdout_filename, mode) as stdout:
        stdout.write(out)
    with open(stderr_filename, mode) as stderr:
        stderr.write(err)

def test_a(fix):
    print("lolcatz")
    print("this is a test")
    sys.stderr.write("err")

The stdout and stderr files end up empty after running that test. Using this set of pytest dependencies

certifi (2017.11.5)
pip (9.0.1)
pluggy (0.6.0)
py (1.5.2)
pytest (3.3.1)
setuptools (38.2.4)
six (1.11.0)
wheel (0.30.0)

Steps of replication are

1. Create the above test
2. Run pytest on it.
3. cat /tmp/std* (they will be empty)
4. Downgrade pytest ( pip install autohil==3.2.5 )
5. Run the test again
6. cat /tmp/std*

[trrichard]

@nicoddemus I found the error.

https://github.com/nicoddemus/pytest/commit/9919269ed048b6e9147ee3301532e3591b9a112b#diff-d8641d58661f0fa63a36c6f6e85715d9R163

It’s a 1 liner. Remove activate_fixture(item) from teardown. It causes a double start which effectively clears the results before they show up in the fixture.

[nicoddemus]

@AlexanderTyrrell #3830 will also fix that AttributeError: 'tuple' object has no attribute 'out' error. 👍