test.scala

// 2.1 Implement buildCar in parallel (orders in parallel)
def buildCarPar(): Future[Car] = Future.join(
  Factory.newChassis(),
  Factory.newWheels(),
  Future.join(
    Factory.newCylinder(),
    Factory.newPiston()
  ) flatMap { case (cylinder, piston) => buildEngine(cylinder, piston) }
  ) map { case (chassis, wheels, engine) => Car(chassis, wheels, engine) }