The power of atoum, everything in my job should be so simple.

atoum-is-awesome.php

<?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()
}