1--TEST--
2callback function is a closure
3--EXTENSIONS--
4filter
5--FILE--
6<?php
7$callback = function ($var) {
8    return $var;
9};
10$var = "test";
11var_dump(filter_var($var, FILTER_CALLBACK, array('options'=> $callback)));
12?>
13--EXPECT--
14string(4) "test"
15