function marlon_test() {

    if ( wp_fusion()->user->has_tag( 'homework-teacher', get_current_user_id() ) ) {
        return 'HAS IT';
    }

    if ( ! wp_fusion()->user->has_tag( 'homework-teacher', get_current_user_id() ) ) {
        return 'DOES NOT HAVE IT';
    }

}

add_shortcode( 'marlon_test', 'marlon_test' );