Existing loggers are overwritten by file config

[janoskut]

When we use context.config.setup_logging(configfile=...), existing loggers are always overwritten by the new configuration. This is the default behavior by the logging module, and noted with a big warning in https://docs.python.org/3/howto/logging.html#configuring-logging:

Warning: The fileConfig() function takes a default parameter, disable_existing_loggers, which defaults to True for reasons of backward compatibility. This may or may not be what you want, since it will cause any non-root loggers existing before the fileConfig() call to be disabled unless they (or an ancestor) are explicitly named in the configuration. Please refer to the reference documentation for more information, and specify False for this parameter if you wish.

In behave, the before_all() hook is normally invoked only after all other modules are imported, and hence after all file-global loggers are created. While it may be debatable, it is common practice to use file-global loggers such as:

import logging

log = logging.getLogger(__name__)

def foo():
    log.info('using the global logger')

When using such modules in behave with file-config, those global loggers are overwritten, and all modules which use such loggers (e.g. step definitions, or from the system under test) won't provide logging.

I suggest to at least pass all **kwargs to logging.config.fileConfig(), to allow to overwrite this default behavior, or even more change the default behavior to "not disable existing loggers" (and still pass the kwargs to allow control of it).

See the #986.