The problem is with the require_once, you are passing a relative path and that path doesn’t exist.
Assuming the test.php file you want to require is in this path
wp-content/themes/your-theme/views/test.php
You can use the following
require_once locate_template('views/test.php');
Consider using include instead of require_one, if this shortcode is not 100% necessary for your site to function, its best to use include as this way you will not receive a fatal error because that file doesn’t exist.