public function testDuplicateTransition()
 {
     $this->setExpectedException(VerificationError::CLASS, 'Adding the same transition instance twice is not supported.');
     $transiton = new Transition('editing', 'approval');
     $builder = new StateMachineBuilder();
     $builder->addTransition($transiton, 'promote')->addTransition($transiton, 'promote');
 }