Adds an additional check to the Site Health plugin for the intl (internationalization) module

check-intl.php

<?php
/**
 * Filter PHP modules for testing
 *
 * @package Normalizer
 */

/**
 * Plugin Name: Check for intl PHP module
 * Description: Add intl module for testing in Site Health
 * Plugin URI:  http://torstenlandsiedel.de
 * Version:     1.0
 * Author:      Torsten Landsiedel
 * Author URI:  https://torstenlandsiedel.de
 * Licence:     GPL 2
 * License URI: http://opensource.org/licenses/GPL-2.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}

/**
 * Add intl module for testing
 *
 * @param  array $modules Recommended PHP modules.
 * @return array          Recommended PHP modules.
 */
function add_intl_module_testing( $modules ) {
	$modules['intl'] = array(
    //You can check for the function ...
		//'function' => 'normalizer_normalize',
    // or for the extension itself:
		'extension' => 'intl',
		'required'  => true,
	);

	return $modules;
}
add_filter( 'site_status_test_php_modules', 'add_intl_module_testing', 11 );