How to mock an Akka Actor to Unit Test a class?

Question

I have a Controller class which controls the requests sent to a Akka actor which is injected in to the controller.

Controller's code:

class Controller(actor: ActorRef) {
  def control(msg: String): Future[String] = {
    actor.ask(msg)(Timeout(2 seconds)).mapTo[String]
  }
}

And my Actor's code is:

class ActorA extends Actor {
  override def receive: Receive = {
    case msg: String => sender ! msg
    case msg: Int => sender ! msg.toString
    case _ => "Invalid command!"
}

Now I need to mock ActorA's behaviour to unit test Controller. Is there a way to do so via Akka TestKit ?