parametrized pytest - how to run concurrently

Hey,

I have a parametrize snippet looking like:

scenarios: List[Tuple[str, Dict[str, str]]] = load_scenarios()

for scenario in scenarios:
    idlist.append(scenario[0])
    items = scenario[1].items()
    argnames = [item[0] for item in items]
    argvalues.append([item[1] for item in items])
metafunc.parametrize(argnames, argvalues, ids=idlist, scope='class')

This collects 263 total tests. I am going to add a few other tests and the total collected with scenarios will ballon to ~780. Don’t ask. Each indidivual test takes about 1-2.5s. Based on this parametrize collection, pytest-parallel and xdist are not gonna work, at least not so far as I’ve tried testing. How might I actually get these concurrent?

Also - each of the 263 tests spawns a Popen.

[asottile]

yeah, my point was that mutating pytest.setup_completed will not be reflected in other processes

[artis3n]

Ok, got it working after removing the nonce. Full snippets for future people that come to this issue:

@pytest.fixture(autouse=True, scope='session')
def all_prep(dependency_dir, global_dependency_dir) -> None:
    """
    Runs all pre- and post-test setup and teardown.
    :param dependency_dir: Path to the dependency directory for this test session
    :param global_dependency_dir: Path to the inter-session dependency directory
    :return: None
    """
    this_worker = os.environ['PYTEST_XDIST_WORKER']
    setup_complete_file = dependency_dir / 'setup_complete'  # pathlib.Path

    # Only one worker should run the setup. The rest will block until it is complete.
    if this_worker == 'gw0':
        # Setup
        server = setup_server(dependency_dir, global_dependency_dir)
        setup_other_stuff(global_dependency_dir)
        complete_setup(setup_complete_file)

        try:
            yield  # Return execution to parent pytest method, run test suite, then move to the 'finally' block
        finally:
            # Teardown
            teardown_server(server)
            setup_complete_file.unlink()  # Delete the setup_complete file

    else:
        wait_for_setup_to_complete(setup_complete_file)
        yield  # Worker returns execution to parent to run test suite


def complete_setup(complete: Path):
    complete.touch()


def wait_for_setup_to_complete(complete: Path):
    # Block until setup has been completed
    while not complete.exists():
        sleep(2)