Summary
Pytest's caplog fixture is a critical part of testing. I'd love to move to loguru, but loguru doesn't seem to work with caplog.
I'm not sure if this is user error (perhaps it's documented somewhere? I haven't been able to find it.), if it is some design oversight/choice, or if the problem is actually on pytest's end.
Expected Result
Users should be able to use loguru as a drop-in replacement for the stdlib logging package and have tests that use the caplog fixture still work.
Actual Result
Drop-in replacement causes tests that use the caplog pytest fixture to fail.
Steps to Reproduce
Base test file
# test_demo.py
import pytest
import logging
logger = logging.getLogger()
logger.addHandler(logging.StreamHandler())
# from loguru import logger
def some_func(a, b):
if a < 1:
logger.warning("Oh no!")
return a + b
def test_some_func_logs_warning(caplog):
assert some_func(-1, 2) == 1
assert "Oh no!" in caplog.text
if __name__ == "__main__":
some_func(-1, 1)
print("end")Without Loguru:
$ python test_demo.py
Oh no!
end
(.venv) Previous Dir: /home/dthor
09:59:56 dthor@Thorium /home/dthor/temp/loguru
$ pytest
========================== test session starts ==========================
platform linux -- Python 3.6.7, pytest-4.3.0, py-1.8.0, pluggy-0.8.1
rootdir: /home/dthor/temp/loguru, inifile:
collected 1 item
test_demo.py . [100%]
======================= 1 passed in 0.03 seconds ========================
With Loguru:
Adjust test_demo.py by commenting out stdlib logging and uncommenting loguru:
...
# import logging
# logger = logging.getLogger()
# logger.addHandler(logging.StreamHandler())
from loguru import logger
...
$ python test_demo.py
2019-02-22 10:02:35.551 | WARNING | __main__:some_func:9 - Oh no!
end
(.venv) Previous Dir: /home/dthor
10:02:35 dthor@Thorium /home/dthor/temp/loguru
$ pytest
========================== test session starts ==========================
platform linux -- Python 3.6.7, pytest-4.3.0, py-1.8.0, pluggy-0.8.1
rootdir: /home/dthor/temp/loguru, inifile:
collected 1 item
test_demo.py F [100%]
=============================== FAILURES ================================
______________________ test_some_func_logs_warning ______________________
caplog = <_pytest.logging.LogCaptureFixture object at 0x7f8e8b620438>
def test_some_func_logs_warning(caplog):
assert some_func(-1, 2) == 1
> assert "Oh no!" in caplog.text
E AssertionError: assert 'Oh no!' in ''
E + where '' = <_pytest.logging.LogCaptureFixture object at 0x7f8e8b620438>.text
test_demo.py:14: AssertionError
------------------------- Captured stderr call --------------------------
2019-02-22 10:02:37.708 | WARNING | test_demo:some_func:9 - Oh no!
======================= 1 failed in 0.20 seconds ========================Version information
$ python --version
Python 3.6.7
(.venv) Previous Dir: /home/dthor
10:10:03 dthor@Thorium /home/dthor/temp/loguru
$ pip list
Package Version
---------------------- -----------
ansimarkup 1.4.0
atomicwrites 1.3.0
attrs 18.2.0
better-exceptions-fork 0.2.1.post6
colorama 0.4.1
loguru 0.2.5
more-itertools 6.0.0
pip 19.0.3
pkg-resources 0.0.0
pluggy 0.8.1
py 1.8.0
Pygments 2.3.1
pytest 4.3.0
setuptools 40.8.0
six 1.12.0
(.venv) Previous Dir: /home/dthor
10:10:07 dthor@Thorium /home/dthor/temp/loguru
$ uname -a
Linux Thorium 4.4.0-17763-Microsoft #253-Microsoft Mon Dec 31 17:49:00 PST 2018 x86_64 x86_64 x86_64 GNU/Linux
(.venv) Previous Dir: /home/dthor
10:11:33 dthor@Thorium /home/dthor/temp/loguru
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.2 LTS
Release: 18.04
Codename: bionic
Summary
Pytest's
caplogfixture is a critical part of testing. I'd love to move to loguru, but loguru doesn't seem to work withcaplog.I'm not sure if this is user error (perhaps it's documented somewhere? I haven't been able to find it.), if it is some design oversight/choice, or if the problem is actually on pytest's end.
Expected Result
Users should be able to use
loguruas a drop-in replacement for the stdlibloggingpackage and have tests that use thecaplogfixture still work.Actual Result
Drop-in replacement causes tests that use the
caplogpytest fixture to fail.Steps to Reproduce
Base test file
Without Loguru:
With Loguru:
Adjust
test_demo.pyby commenting out stdlibloggingand uncommentingloguru:Version information
$ python --version Python 3.6.7 (.venv) Previous Dir: /home/dthor 10:10:03 dthor@Thorium /home/dthor/temp/loguru $ pip list Package Version ---------------------- ----------- ansimarkup 1.4.0 atomicwrites 1.3.0 attrs 18.2.0 better-exceptions-fork 0.2.1.post6 colorama 0.4.1 loguru 0.2.5 more-itertools 6.0.0 pip 19.0.3 pkg-resources 0.0.0 pluggy 0.8.1 py 1.8.0 Pygments 2.3.1 pytest 4.3.0 setuptools 40.8.0 six 1.12.0 (.venv) Previous Dir: /home/dthor 10:10:07 dthor@Thorium /home/dthor/temp/loguru $ uname -a Linux Thorium 4.4.0-17763-Microsoft #253-Microsoft Mon Dec 31 17:49:00 PST 2018 x86_64 x86_64 x86_64 GNU/Linux (.venv) Previous Dir: /home/dthor 10:11:33 dthor@Thorium /home/dthor/temp/loguru $ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 18.04.2 LTS Release: 18.04 Codename: bionic