Best WP test function

file.php

<?php
/**
 *  Usage:
 *  $something = 'string';
 *  $something = array('key' => 'value', $something);
 *  do_action('testlog', $something);
 */
 
 add_action('testlog', 'do_testlog');
 function do_testlog($arg) {
	 if(is_array($arg)) {
		 $arg = print_r($arg, true);
	 }
	 if(is_object($arg)) {
		 $arg = serialize($arg);
	 }
	 file_put_contents( ABSPATH . 'testlog.txt', $arg . PHP_EOL, FILE_APPEND );
 }