<?php

class Test
{
    public function foo()
    {
        $foo = 'foo';
        var_dump($foo);
    }

    public function bar()
    {
        $bar = 'bar';
        return $bar;
    }

    public function __debugInfo()
    {
        echo 'debugInfo';
        echo $this->bar();
        return ['foo' => 'bar'];
    }
}

phpinfo();
$test = new Test();
$test->foo();