Why are loggers not propogating when I run pytest

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I'm unable to get logging output from my unit tests and it looks like the reason is that all loggers except for the root logger have propagate set to false when I run pytest. I can run the following file, using pytest and python test_file.py. In the former logging.getLogger('one').propagate == True while in the latter logging.getLogger('one').propagate == False. Why is this?

test_file.py

import logging

def test_function():
  print()
  print('root', logging.getLogger().propagate)
  print('one', logging.getLogger('one').propagate)

if __name__ == '__main__':
  test_function()

How do I get all my loggers to propagate? Searching the internet only turns up questions about how to turn off propagation as if most people have the opposite experience that I do.

pytest logging python
1 Answers

This isn't a problem with pytest. I searched the cpython and pytest source code for anything that would do this and found nothing. Then I stepped through the getLogger code and found that something was calling the logging.setLoggerClass function and replacing the logger class with a subclass that sets propagate to false. I set a breakpoint on setLoggerClass and found that a pytest plugin provided by ROS2 was doing this. I added the following to pytest.ini and now everything works great.

[pytest]
addopts = -p no:launch -p no:launch_ros
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