icaotix_python_logging/tests/test_basic_logger.py

import io
import json
import logging
import logging.handlers
import unittest
from unittest.mock import patch

from src.icaotix_python_logging import logger


class TestBasicLogger(unittest.TestCase):

    def test_creation(self):
        log = logger.get_stdout_logger("test_basic_logger")
        self.assertIsInstance(log, logging.Logger)
        self.assertEqual(1, len(log.handlers))
        self.assertIsInstance(log.handlers[0], logging.handlers.QueueHandler)

    @patch('sys.stdout', new_callable=io.StringIO)
    def test_single_log_message(self, stdout: io.StringIO):
        log = logger.get_stdout_logger("test_basic_logger")
        log.info("Hello world")

        # wait for all writes to be done (type is checked in test above)
        log.handlers[0].listener.queue.join()

        actual_json = json.loads(stdout.getvalue())
        self.assertEqual(actual_json, actual_json | {"logger": "test_basic_logger", "message": "Hello world"})


if __name__ == '__main__':
    unittest.main()