py.test + xdist запуск с -n N>1 и fixture(scope='module')

kixiro · 14.Сентябрь.2016 10:14:42

Пытаюсь наладить параллельный запуск тестов, в каждом модуле с тестами несколько отдельных функций, использующих fixture-у с scope=‘module’ и подразумевается что на каждый модуль будет запущена одна такая, но при запуске с xdist в несколько потоков, разбиение тестов происходит не по модулям и на каждый поток вызывается свой вызов fixture-ы. Как сделать, чтобы тесты бились по модулям в потоках?

Sergey_Pirogov · 14.Сентябрь.2016 18:38:16

Сегодня столкнулся с такой же проблемой

ex3me0 · 23.Октябрь.2016 06:56:27

Гугол?

github.com/pytest-dev/pytest

Allow fixtures to execute only once per session even if parallel running (xdist) is enabled

opened 12:39PM - 17 Jan 13 UTC

closed 07:21PM - 23 Jun 17 UTC

pytestbot

type: enhancement plugin: xdist

Originally reported by: **BitBucket: [inklesspen](http://bitbucket.org/inklesspe…n), GitHub: [inklesspen](http://github.com/inklesspen)** --- Explanation copy-pasted from https://gist.github.com/4555229 Pytest's session fixture scope is really handy, but there are some things which need to execute only once per actual test session. For example, one of my session fixtures sets up DB tables at the start of the test session and tears them down at the end. (I use PostgreSQL's nested transactions to keep from having to drop and recreate tables between each individual test.) This works great when tests are run sequentially, but when you try to run them in parallel using the pytest-xdist plugin (py.test -n4), each test runner individually tries to create and drop the tables, which simply doesn't work well. I'm informed an alternative that does work is to use the pytest_sessionstart plugin function, but unfortunately this means that the fixtures upon which the dbtables depend will also have to be in the sessionstart plugin function, and that gets ugly very quickly. I propose a new scope level provided by pytest-xdist, which provides a session-level scope which executes only once for all test runners, perhaps called 'xdist-session'. When one test runner finds an xdist-session fixture is required, it notifies the master, which then picks one of the slaves to execute the fixture. (The result of the fixture, if any, would need to be execnet-pickleable.) Once the fixture is executed, the master notifies the slaves and they resume running the tests. Likewise, at the end of the test session, the master waits for all the slaves to have finished before instructing the slave to execute any finalizers attached. If the slave dies before executing the finalizers, they wouldn't be executed in this model. This limitation could be mitigated by having the master set up one slave to do nothing but execute xdist-session fixtures; since it won't execute tests, it is less likely to crash. Of course, a test suite is not always run in parallel. Many xdist-session fixtures would easily fall back to running in session scope, but some test suites may need to have two similar but distinct fixtures, so there may need to be a way to have a 'guard' on a fixture so that it isn't used depending on the test invocation. I'm not sure how best to implement this. --- - Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/252

gist.github.com

https://gist.github.com/inklesspen/4555229

README.md

Pytest's session fixture scope is really handy, but there are some things which need to execute only once per actual test session. For example, one of my session fixtures sets up DB tables at the start of the test session and tears them down at the end. (I use PostgreSQL's nested transactions to keep from having to drop and recreate tables between each individual test.)

```python
@pytest.fixture(scope='session')
def dbtables(request, sqlengine):
    Base.metadata.create_all(sqlengine)

    def teardown():
        Base.metadata.drop_all(sqlengine)

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conftest.py

import os

import pytest

from sqlalchemy import engine_from_config

from pyramid.paster import get_appsettings

from ..models import (
    DBSession,

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Один инстанс для всех процессов при параллельном запуске тестов (py.test xdist) python

Увы стандартными доступными методами такое сделать нельзя. В таком случае у вас будет отдельный экземпляр класса для каждого запущенного процесса. Уже была такая тема: И есть даже дефект создан по этому поводу: https://bitbucket.org/hpk42/pytest/issue/175/way-to-control-how-pytest-xdist-runs-tests Тут надо делать какой-то workaround. Я лично не экспериментировал, но все таки считаю что этого можно добиться через хуки, которые вызываются до xdist плагина. Как-то надо будет время выделить для этого задачи ( давно уже висит в todo )