This is a dead simple demo to test Actors with specs2 with Akka TestKit. The code is modified from the demo code at http://doc.akka.io/docs/akka/snapshot/scala/testing.html#Asynchronous_Integration_Testing_with_TestKit, which is for scalatest.
The end result is very simple but I had to take the code apart and put it back together again to understand it.
> sbt testEverything is in the docs, but the part that I didn't notice the first few times I read them was that expectMsg and other assertions don't work for all actors, they only monitor testActor, a special ActorRef provided by TestKit. If you are testing a response from an actor you have to use the non-sugared tell syntax so that testActor gets the response acotor ! (msg, testActor) or mix in the trait with ImplicitSender so that testActor shows up as the sender to all messages send in the test.