Warnings logging doesn't log warnings

Description

The Astropy logging mechanism provides the enable_warnings_logging() function, which is claimed to enable logging of warnings.warn() messages. This does not appear to work.

Expected behavior

Warnings signaled by warnings.warn should be recorded in the log.

Actual behavior

Such warnings do not appear.

Steps to Reproduce

import warnings
from astropy import log
import astropy.logger
import logging

try:
    log.enable_warnings_logging()
except astropy.logger.LoggingError:
    pass

with log.log_to_file("test.log"):
    log.warning("logger warning")
    warnings.warn("warnings warning")

The file test.log should contain both “logger warning” and “warnings warning” but it only contains “logger warning”.

(The exception handling is because the only way to ensure the astropy warnings logging mechanism is turned on is to call the function and catch the exception if it’s already turned on; it is in my completely default setup.)

System Details

>>> import platform; print(platform.platform())
Linux-3.10.0-862.14.4.el7.x86_64-x86_64-with-debian-buster-sid
>>> import sys; print("Python", sys.version)
Python 3.7.6 | packaged by conda-forge | (default, Jun  1 2020, 18:57:50)
[GCC 7.5.0]
>>> import numpy; print("Numpy", numpy.__version__)
Numpy 1.18.5
>>> import astropy; print("astropy", astropy.__version__)
astropy 4.0
>>> import scipy; print("Scipy", scipy.__version__)
Scipy 1.4.1
>>> import matplotlib; print("Matplotlib", matplotlib.__version__)
Matplotlib 3.0.3

[pllim]

@aarchiba , #11562 is merged to clarify the logger usage. Can we close this? Thanks for bringing this to our attention!

[pllim]

Ops… Bot comment is accurate but I used the wrong API key. 😅