test.py

from totest import function
import logging
import click_log


def test_function(caplog):
    click_log.basic_config('test').setLevel(logging.DEBUG)
    caplog.set_level(logging.WARNING)
    assert 1 == function()
    assert caplog.records == 1

totest.py

import logging
import click_log


logger = logging.getLogger('test')
click_log.basic_config('test').setLevel(logging.DEBUG)


def function():
    logger.warning('this is a warning')