protected function getOutputForCommand($command, $commandName, array $args = array(), array $options = array())
{
if (empty($args)) {
$args = array('command' => $commandName);
}
$this->application->add($command);
$applicationCommand = $this->application->find($commandName);
$commandTester = new CommandTester($applicationCommand);
$commandTester->execute($args, $options);
return $commandTester->getDisplay();
}