How do you test loggers? In PHP

Consider the following class:

<?php

namespace EveOnline\Logging;

use Log;
use Monolog\Handler\StreamHandler;
use Monolog\Logger;

class EveLogHandler {

    public function requestLog($response, $fileName) {
        $streamHandler = new StreamHandler(storage_path($fileName), Logger::INFO);
        $logInstance   = Log::getMonolog();

        $logInstance->setHandlers(array($streamHandler));
        $logInstance->addInfo('Fetched', [$response->getStatusCode(), $response->getBody()->getContents()]);
        $response->getBody()->rewind();
    }

    public function messageLog($message, $fileName) {
        $streamHandler = new StreamHandler(storage_path($fileName), Logger::INFO);
        $logInstance   = Log::getMonolog();

        $logInstance->setHandlers(array($streamHandler));
        $logInstance->addInfo('Message', [$message]);
    }
}

Now this is used in my library I am building to log out guzzle responses and up until now I have been mocking out this class with its methods.

Two things:

How do you test it? Like how would I test this class? How do I verify that a file was written to or do I?

Second part and most important storage_path is a laravel global function. This library is separate of laravel. But is intended to be used with laravel. So how do I get around this function ??