Run a pytest test in a fork

pytest_fork.py

def run_test_in_fork(func, *args, **kwargs):
    """Run a pytest test in a fork of the pytest process.

    Useful to check behaviour of some code when run in a forked process.
    The test outcome will be reported normally in the pytest parent.
    """
    if not hasattr(os, "fork"):
        pytest.skip("os.fork not available")
    error_in_child = multiprocessing.Value("b")
    child_pid = os.fork()
    if child_pid:
        # We are the parent
        os.waitpid(child_pid, 0)
        assert not error_in_child.value
    else:
        # We are the child
        try:
            func(*args, **kwargs)
        except Exception:
            error_in_child.value = True
            raise
        # Stop running other tests of this test suite in the child
        pytest.exit("Stop tests in child")


def test_something_in_fork():
    run_test_in_fork(_test_something_in_fork_inner)


def _test_something_in_fork_inner():
    assert 1 + 1 == 2