def METHOD_NAME(mocker, caplog):
    """
    Verify that `mqttwarn.commands.run_mqttwarn` works as expected.
    Here, a configuration file is obtained using the `--config-file` command line option.
    """
    mocker.patch("sys.argv", ["mqttwarn-custom"])
    mocker.patch("mqttwarn.commands.subscribe_forever")
    mqttwarn.commands.run_mqttwarn(configfile="tests/etc/no-functions.ini")
    assert caplog.messages == [
        "Starting mqttwarn-custom",
        "Log level is DEBUG",
    ]