This does not compile since ImplicitSender depends on TestKit and not TestKitBase. Error message: "illegal inheritance; self-type demo.EchoSpec does not conform to akka.testkit.ImplicitSender's selftype akka.testkit.ImplicitSender with akka.testkit.TestKit [---] line 18"

EchoSpec.scala

package demo

import org.scalatest._
import akka.testkit.TestKit
import akka.actor.Actor
import akka.actor.ActorSystem
import akka.testkit.TestKitBase
import akka.testkit.ImplicitSender
import akka.actor.Props

class Echo extends Actor {
	def receive = { 
		case msg => sender ! msg
	}
}

class EchoSpec extends FlatSpec with Matchers 
	with TestKitBase with BeforeAndAfterAll with ImplicitSender { // this does not compile with Akka 2.2.3
  
	implicit lazy val system = ActorSystem()
  
  override def afterAll = system.shutdown
	
  "An actor" should "echo a message" in {
  	val echoActor = system.actorOf(Props[Echo], "echo")
  	echoActor ! "hello there"
  	expectMsg("hello there")
	}
}