FYI, on windows, the vlaues for LOG_* "log-levels" are as followed:

<?php
namespace Test;

include 'vendor/autoload.php';

use Psr\Log\LogLevel;

$log_levels = array(
    LogLevel::EMERGENCY => LOG_EMERG,
    LogLevel::ALERT => LOG_ALERT,
    LogLevel::CRITICAL => LOG_CRIT,
    LogLevel::ERROR => LOG_ERR,
    LogLevel::WARNING => LOG_WARNING,
    LogLevel::NOTICE => LOG_NOTICE,
    LogLevel::INFO => LOG_INFO,
    LogLevel::DEBUG => LOG_DEBUG,
);

print_r($log_levels);
/*
prints:

Array
(
    [emergency] => 1
    [alert] => 1
    [critical] => 1
    [error] => 4
    [warning] => 5
    [notice] => 6
    [info] => 6
    [debug] => 6
)
*/