This producer will not send anything to rabbitmq but will execute instantly the consumer
Inheritance: implements Knp\Bundle\KnpBundlesBundle\Producer\ProducerInterface
 public function testExecution()
 {
     $consumer = $this->getMock('OldSound\\RabbitMqBundle\\RabbitMq\\ConsumerInterface');
     $consumer->expects($this->once())->method('execute');
     $producer = new ExecutorProducer($consumer);
     $producer->publish('a message');
 }