How to spec a Symfony2 console command?

FindPackageListsCommand.php

<?php

namespace Zalas\Bundle\PackagistBundle\Command;

use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Input\InputOption;
use Symfony\Component\Console\Output\OutputInterface;

class FindPackageListsCommand extends ContainerAwareCommand
{
    protected function configure()
    {
        $this->setName('packagist:crawl:package-lists');
        $this->addOption('batch-size', 'bs', InputOption::VALUE_REQUIRED, 'The batch size', 100);
    }

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $finder = $this->getContainer()->get('zalas_packagist.package_list_page_finder');
        $finder->setBatchSize($input->getOption('batch-size'));
        $finder->run('https://packagist.org');
    }
}

FindPackageListsCommandSpec.php

<?php

namespace spec\Zalas\Bundle\PackagistBundle\Command;

use PhpSpec\ObjectBehavior;
use Prophecy\Argument;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Zalas\Packagist\Worker\PackageListFinder;

class FindPackageListsCommandSpec extends ObjectBehavior
{
    function let(InputInterface $input, PackageListFinder $packageListPageFinder)
    {
        $input->bind(Argument::cetera())->willReturn();
        $input->isInteractive()->willReturn(false);
        $input->validate()->willReturn();
        $input->getOption('batch-size')->willReturn(1);

        $packageListPageFinder->setBatchSize(Argument::cetera())->willReturn();
    }

    function it_is_a_container_aware_command()
    {
        $this->shouldHaveType('Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand');
    }

    function it_has_a_name()
    {
        $this->getName()->shouldReturn('packagist:crawl:package-lists');
    }

    function it_runs_the_package_list_page_finder(ContainerInterface $container, InputInterface $input, OutputInterface $output, PackageListFinder $packageListPageFinder)
    {
        $container->get('zalas_packagist.package_list_page_finder')->willReturn($packageListPageFinder);

        $packageListPageFinder->run('https://packagist.org')->shouldBeCalled();

        $this->setContainer($container);
        $this->run($input, $output);
    }

    function it_sets_the_batch_size_if_given(ContainerInterface $container, InputInterface $input, OutputInterface $output, PackageListFinder $packageListPageFinder)
    {
        $batchSize = 100;

        $container->get('zalas_packagist.package_list_page_finder')->willReturn($packageListPageFinder);
        $input->getOption('batch-size')->willReturn($batchSize);

        $packageListPageFinder->setBatchSize($batchSize)->shouldBeCalled();
        $packageListPageFinder->run('https://packagist.org')->willReturn();

        $this->setContainer($container);
        $this->run($input, $output);
    }
}