Failing a scalatest when akka actor throws exception outside of the test thread

Question

I\'ve had a situation come up and bite me a few times where I\'m testing an Actor and the Actor throws an exception unexpectedly (due to a bug), but the test still passes.

Answer 1

Other than examining the logs, I can think of two ways to fail tests when an actor crashes:

• Ensure that no Terminated message is received
• Check the TestActorRef.isTerminated property

The latter option is deprecated, so I'll ignore it.

Watching Other Actors from Probes describes how to setup a TestProbe. In this case it might look something like:

val probe = TestProbe()
probe watch ref

// Actual test goes here ...

probe.expectNoMessage()

If the actor dies due to an exception it will generate the Terminated message. If that happens during the test and you expect something else, the test will fail. If it happens after your last message expectation, then the expectNoMessage() should fail when Terminated is received.