Pytest: Cannot disable capturing with --dist=distmode

[pytestbot]

Originally reported by: Lucas Cimon (BitBucket: LucasC, GitHub: LucasC)

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To reproduce this issue, create a file named stupid_test.py with the following code :

def test_unicode():
    print "*[PRINT TO STDOUT]*"
    assert True

Then run the following:

$ py.test -v --capture=no --tx='1*popen' --dist=no stupid_test.py
# -> standard output contains "*[PRINT TO STDOUT]*"
$ py.test -v --capture=no --tx='1*popen' --dist=load stupid_test.py
# -> standard output is captured
$ py.test -v --capture=no --tx='1*popen' --dist=each stupid_test.py
# -> standard output is captured

I'm using the following version:

platform linux2 -- Python 2.7.6 -- py-1.4.26 -- pytest-2.6.4 -- /usr/bin/python

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• Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/680

[pytestbot]

_Original comment by_ Lucas Cimon (BitBucket: LucasC, GitHub: LucasC):

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I had a quick look on how are nodes set up in pytest-xdist slavemanage.py.
It looks like stdout / stderr could be aggregated & redirected using the method described in this pytest-dev thread and attachment by @hpk42.

Would that be a reasonable solution ?

[pytestbot]

_Original comment by_ Ragnar Rova (BitBucket: ragnar_rova, GitHub: ragnar_rova):

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I have a similar issue, running tests that run fabric like so:

py.test -s -n4 --boxed

...

#!python

fabric_env/lib/python2.7/site-packages/fabric/io.py:211: in input_loop
    r, w, x = select([sys.stdin], [], [], 0.0)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <_pytest.capture.DontReadFromInput instance at 0x1053563b0>

    def fileno(self):
>       raise ValueError("redirected Stdin is pseudofile, has no fileno()")
E       ValueError: redirected Stdin is pseudofile, has no fileno()

fabric_env/lib/python2.7/site-packages/_pytest/capture.py:441: ValueError

[pytestbot]

_Original comment by_ Ragnar Rova (BitBucket: ragnar_rova, GitHub: ragnar_rova):

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This got me halfway, but introduced other errors: http://stackoverflow.com/questions/27006884/pytest-xdist-without-capturing-output

[szevzol]

I would like to do the same, disabling capture while using --dist-load.

I was able to do this by logging everything in my tests to STDERR. It was working fine until pytest release 2.6.0. In that release commit ce8678e modified something, which I don't understand yet. After that I cannot disable capturing at all with --dist=load.

Can anyone please help me to understand why it is not possible to disable capturing when distributing tests? Maybe there's a good reason I'm not aware of.

[nicoddemus]

Can anyone please help me to understand why it is not possible to disable capturing when distributing tests? Maybe there's a good reason I'm not aware of.

I don't think is there any specific reason for that: I think it works like this because that's how the pytest runner works by default, and each slave uses the default option for capturing. I think all it is required is for the master node to pass that configuration along to the slaves.

[szevzol]

Thank you nicoddemus! I'm going to dig deeper in xdist and pytest to figure out the solution ;)

[szevzol]

This got me halfway, but introduced other errors: http://stackoverflow.com/questions/27006884/pytest-xdist-without-capturing-output

This suggestion is working for me however

• it always turns off capturing.
• it only prints STDERR but not STDOUT

If I do this:

capman._method = str(config.getoption("--capture"))

Instead of this:

capman._method = "no"

Then I can turn on and off capturing STDERR during distributed tests.

[nicoddemus]

Fixed in #1124

[nitrocode]

I'm using -n3 -d and each of my tests have print statements that are ignored by pytest. Im using pytest 2.9.1 and pytest-xdist-1.14.

py.test -sv -rx --color=yes -n3 -d --junit-xml=output.xml
py.test -sv -rx --color=yes -n3 -d --junit-xml=output.xml --capture=no

How do I see stdout? Doesn't appear in my junit xml file either when I'm parallelizing the tests.

[mloskot]

I'm using 2.9.1 on Windows with Python 3.5 and, similarly to @nitrocode, I also can not see my print outputs while using -n N. Running without xdist prints output to console as expected.

[RonnyPfannschmidt]

currently cdist and nocapture is not compatible, the next major version of xdist will be