function custom_cpt_testimonial() {
    $labels = array(
        'name' => _x('Testimonials', 'Post Type General Name'),
        'singular_name' => _x('Testimonial', 'Post Type Singular Name'),
        'menu_name' => 'Testimonials'
    );
    $args = array(
        'labels' => $labels,
        'public' => true,
        'menu_position' => 5,
        'supports' => array('title', 'editor', 'thumbnail', 'excerpt'),
        'has_archive' => true,
        'menu_icon' => 'dashicons-admin-appearance',
        'rewrite' => array('slug' => 'testimonial'),
    );
    register_post_type('testimonial', $args);
}
add_action('init', 'custom_cpt_testimonial');