Possible to collect all pytest tests inside python

[jscotka]

Hi,
I wanted to generate metadata for another project based on pytest tests (https://github.com/jscotka/fmf_metadata/)
And I was not able to create own implementation of pytest --collect-only in python

I need something like this pseudo code:

import pytest
import _pytest
def collect()
    conf = _pytest.get_config("path_to_config")
    sess = session.Session(conf)
    sess.collect()
    return sess.items

I've tried to do that (playing wih config, session. fscollector, pluginmanager and more) but finally I was not successful and I had to workaround it by using autouse fixture with scope="session", but it needs to add this fixture into contest.py https://github.com/jscotka/fmf_metadata/blob/main/fmf_metadata/pytest_fixture.py

My idea is to have offline tool without modifying test code itself.

Is there any way to do it, could anyone help me to implement it ?

[hoefling]

I gave an answer to a similar question a while ago: you can register a plugin that stores the items and run pytest.main with the plugin supplied. Example code:

import pytest


class ItemsCollector:
    def pytest_collection_modifyitems(self, items):
        self.items = items[:]


def main():
    collector = ItemsCollector()
    pytest.main(['--collect-only'], plugins=[collector])
    print("collected items:", collector.items)

It would be interesting to know though whether a better approach exists.

[RonnyPfannschmidt]

this one is the best approach as of now

[jscotka]

@hoefling many thanks.

[nicoddemus]

A quick note: you probably also want to pass -p no:terminal to suppress all pytest output:

pytest.main(['--collect-only', '-pno:terminal'], plugins=[collector])

[nicoddemus]

@jscotka could you mark @hoefling's answer as accepted? This helps others looking for the same solution in the future. Thanks!

[jscotka]

Hi @nicoddemus thanks a lot. This terminal supress suggestion is great. Yes I'll mark it as accepted.

[jscotka]

Hi,
finally I've found the solution for my question, I don'tknow if this solution is optimal, but works as exoected for me. Maybe if anybody have time, could me help me to do it more optimal if possible.

from _pytest import config
from _pytest.main import Session


def collect(opts):
    conf = config.get_config(opts, plugins=[])
    conf.parse(opts)
    conf._do_configure()
    sess = Session.from_config(config=conf)

    conf.hook.pytest_sessionstart(session=sess)
    conf.hook.pytest_collection(session=sess)
    conf.hook.pytest_collection_finish(session=sess)

    return sess.items

[RonnyPfannschmidt]

@hoefling provided a much better solution, yours is hooking into internals it shouldn't touch

the stuff you use is something i intend to break within the next 6 months

[jscotka]

@RonnyPfannschmidt
Thank you very much. It is exactly point where I had fear to use this solution.