Empty Messages In Caplog When Logs Emmited In A Different Process

I am running the test with log_cli=true. The script: import logging import sys from multiprocessing import Process logging.basicConfig(stream=sys.stderr, level=logging.DEBUG) log

Solution 1:

Inspired by @hoefling and still the will to use caplog, there is a solution. The idea is to create a fixture, which takes the queue from the QueueHandler handler and reemits the logs in the main process, which is capturable by the caplog

import logging
import sys
from contextlib import contextmanager
from logging import handlers
from multiprocessing import Process, Queue

import pytest

logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)


logger = logging.getLogger(__name__)


class ActorContext:
    def __init__(self):
        self.log = logger

    def run(self):
        self.log.debug("Some msg")


current_actor_context = ActorContext()


@pytest.fixture()
def caplog_workaround():
    @contextmanager
    def ctx():
        logger_queue = Queue()
        logger = logging.getLogger()
        logger.addHandler(handlers.QueueHandler(logger_queue))
        yield
        while not logger_queue.empty():
            log_record: logging.LogRecord = logger_queue.get()
            logger._log(
                level=log_record.levelno,
                msg=log_record.message,
                args=log_record.args,
                exc_info=log_record.exc_info,
            )

    return ctx


def test_caplog_already_not_fails(caplog, caplog_workaround):
    with caplog.at_level(logging.DEBUG, logger="leapp.actors.quagga_report"):
        with caplog_workaround():
            p = Process(target=current_actor_context.run)
            p.start()
            p.join()
    assert "Some msg" in caplog.text


def test_caplog_passes(caplog, capsys):
    with caplog.at_level(logging.DEBUG, logger="leapp.actors.quagga_report"):
        current_actor_context.run()
    assert "Some msg" in caplog.text