filter-nav-menus.php

<?php

// Add a custom menu item with the URL "_SITEURL_/test" and label "[test]" to see it in action

add_filter('wp_nav_menu', 'menu_shortcodes');

function menu_shortcodes( $menu ){
  return str_replace('_SITEURL_',preg_replace("~^(?:f|ht)tps?://~i", '', home_url() ), do_shortcode( $menu ) );
}

add_shortcode('test','tester');

function tester(){
	return 'Worked!';
}