The power of atoum, everything in my job should be so simple.
<?php
public function testAddBox()
{
$package = new Entity\Package();
$box = new \Mock\MyLittle\Bundle\BoxBundle\Entity\Box;
$this
->object($package->addBox($box))
->isIdenticalTo($package)
->mock($box)
->call('setPackage')
->withIdenticalArguments($package)
->once()
}