On the other hand, if you add another test_ function there will be no changes in total duration because pytest is actually running both tests in parallel:

#!/usr/bin/env python

import pytest
import time

@pytest.fixture(scope="function", params=["a1", "a2"])
def fix_dummy(request):
    print "fix_dummy: parameter: %s" % (request.param, )
    return request.param

def test_dummy1(fix_dummy):
    print "parameter from fix_dummy: %s" %(fix_dummy, )
    time.sleep(2)

def test_dummy2(fix_dummy):
    print "parameter from fix_dummy: %s" %(fix_dummy, )
    time.sleep(2)




$ py.test -vs test_dummy.py -n 2
====================================================================================== test session starts =======================================================================================
platform linux2 -- Python 2.7.3 -- py-1.4.26 -- pytest-2.6.4 -- /usr/bin/python
plugins: xdist
[gw0] linux2 Python 2.7.3 cwd: /home/gmagno/Desktop/pytest
[gw1] linux2 Python 2.7.3 cwd: /home/gmagno/Desktop/pytest
[gw1] Python 2.7.3 (default, Feb 27 2014, 20:00:17)  -- [GCC 4.6.3]
[gw0] Python 2.7.3 (default, Feb 27 2014, 20:00:17)  -- [GCC 4.6.3]
gw0 [4] / gw1 [4]
scheduling tests via LoadScheduling

test_dummy.py::test_dummy2[a1]
test_dummy.py::test_dummy1[a1]
[gw1] PASSED test_dummy.py::test_dummy1[a1]
[gw0] PASSED test_dummy.py::test_dummy2[a1]
test_dummy.py::test_dummy1[a2]
test_dummy.py::test_dummy2[a2]
[gw1] PASSED test_dummy.py::test_dummy1[a2]
[gw0] PASSED test_dummy.py::test_dummy2[a2]

==================================================================================== 4 passed in 4.66 seconds ====================================================================================

I hope I am not confusing you guys.

Cheers,
Gonçalo

On Sat, Dec 6, 2014 at 9:29 PM, Goncalo Morgado <goncalo.magno@gmail.com> wrote:

I might be missing something very fundamental here, but tests are not running in parallel on my side, as you may see tests are taking 4 seconds-ish:

$ py.test -vs test_dummy.py -n 2
====================================================================================== test session starts =======================================================================================
platform linux2 -- Python 2.7.3 -- py-1.4.26 -- pytest-2.6.4 -- /usr/bin/python
plugins: xdist
[gw0] linux2 Python 2.7.3 cwd: /home/gmagno/Desktop/pytest
[gw1] linux2 Python 2.7.3 cwd: /home/gmagno/Desktop/pytest
[gw0] Python 2.7.3 (default, Feb 27 2014, 20:00:17)  -- [GCC 4.6.3]
[gw1] Python 2.7.3 (default, Feb 27 2014, 20:00:17)  -- [GCC 4.6.3]
gw0 [2] / gw1 [2]
scheduling tests via LoadScheduling

test_dummy.py::test_dummy1[a1]
[gw1] PASSED test_dummy.py::test_dummy1[a1]
test_dummy.py::test_dummy1[a2]
[gw1] PASSED test_dummy.py::test_dummy1[a2]

==================================================================================== 2 passed in 4.47 seconds ====================================================================================

Cheers,

Gonçalo

On Sat, Dec 6, 2014 at 8:52 PM, Bruno Oliveira <nicoddemus@gmail.com> wrote:

Thanks for the example. 

I tried and it seems that xdist is running the tests in parallel: the more CPUs I use, the fastest the test suite runs. Do you see a different behavior?

Cheers,

On Sat, Dec 6, 2014 at 5:12 PM, Goncalo Morgado <goncalo.magno@gmail.com> wrote:

To better depict what I am saying follows some code.

$ sudo pip install pytest

$ sudo pip install pytest-xdist

$ py.test -vs test_dummy.py -n 2

#!/usr/bin/env python

"""

This is test_dummy.py

"""
import pytest
import time

@pytest.fixture(scope="function", params=["a1", "a2"])
def fix_dummy(request):
    print "fix_dummy: parameter: %s" % (request.param, )
    return request.param

def test_dummy1(fix_dummy):
    print "parameter from fix_dummy: %s" %(fix_dummy, )
    time.sleep(2)

Cheers,
Gonçalo

On Sat, Dec 6, 2014 at 6:45 PM, Goncalo Morgado <goncalo.magno@gmail.com> wrote:

pytest-xdist helped me to run different tests in multiple CPUs, for instance test_foo() and test_bar() would easily be run in two CPUs with pytest-xdist. The problem is when you have test_foobar(some_fixture), where some_fixture is parametrized with, let's say two parameters ["a", "b"], which will lead to two different test runs of test_foobar(). The challenge is to have these two test runs running in two CPUs.

Cheers
Gonçalo

On Sat, Dec 6, 2014 at 6:30 PM, Bruno Oliveira <nicoddemus@gmail.com> wrote:

Have you tried using pytest-xdist?

Cheers,

On Sat, Dec 6, 2014 at 4:26 PM, Goncalo Morgado <goncalo.magno@gmail.com> wrote:

Hi pytest community,

I am not sure this is the right place to ask this, and I am sorry if it's not.

I am trying to make use of multiple CPUs to run my tests, which I can for separately defined tests (different test_ functions for instance). The challenge is to run tests, generated from one single test_ function which fixture it depends on is parametrized with multiple parameters, on multiple CPUs.
Currently I have this test that generates more than a thousand tests (because of the parametrized fixture it depends on) and ends up being very time consuming to run in one single CPU.

Thanks for this great tool that is pytest!

Cheers,
Gonçalo

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