Menu item active class.

menu_item_class.php

<?php
/*
 * Menu item active class.
 */
function add_current_nav_class($classes, $item) {
    // get current post details
    global $post;

    // get post type of current post
    $current_post_type = !empty($post) ? get_post_type_object($post->post_type) : null;
    $current_post_type_slug = $current_post_type && isset($current_post_type->rewrite['slug']) ? $current_post_type->rewrite['slug'] : ( $current_post_type && $current_post_type->name == 'post' ? 'news' : null);


    // get URL of the menu item
    $menu_slug = strtolower(trim($item->url));

    // if menu item URL contains current post types slug add current-menu-item class
    if ( $current_post_type_slug ) {
        if ( strpos($menu_slug, $current_post_type_slug) !== false ) {
           $classes[] = 'current-menu-item';
        }
    }

    // return corrected set of classes to add to menu item
    return $classes;
}
add_action('nav_menu_css_class', 'add_current_nav_class', 10, 2 );