NPE using assertAllStagesStopped

[cchantep]

Upgrading from Akka 2.4.x with Contrib 0.6 to Akka 2.5 with Contrib 0.8 a NPE is raised from the .assertAllStagesStopped utility.

java.lang.NullPointerException: null (PhasedFusingActorMaterializer.scala:483)
  akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:483)
  akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:424)
  akka.stream.impl.PhasedFusingActorMaterializer.materialize(PhasedFusingActorMaterializer.scala:415)
  akka.stream.scaladsl.RunnableGraph.run(Flow.scala:439)
  akka.stream.scaladsl.Source.runWith(Source.scala:83)
  anorm.AkkaStreamSpec.run$1(AkkaStreamSpec.scala:43)
  anorm.AkkaStreamSpec.$anonfun$new$26(AkkaStreamSpec.scala:67)
  anorm.AkkaStreamSpec$$Lambda$664/60669686.apply(Unknown Source)
  anorm.AkkaStreamSpec.$anonfun$new$25(AkkaStreamSpec.scala:67)
  anorm.AkkaStreamSpec$$Lambda$647/220505170.apply(Unknown Source)
  akka.stream.contrib.TestKit$.assertAllStagesStopped(TestKit.scala:29)
  anorm.AkkaStreamSpec.$anonfun$new$24(AkkaStreamSpec.scala:66)
  anorm.AkkaStreamSpec$$Lambda$634/1871985180.apply(Unknown Source)

[johanandren]

assertAllStagesStopped relies on internals (which has changed with the new materializer in 2.5), it was copied here from Akka core 2.4. Was it not available as a public testkit method in the 2.4 branch or why was it copied?

[cchantep]

It was extracted, as useful, and no longer works

[johanandren]

Yeah, but why didn't we just use the one from the akka-streams-teskit instead of copying the sources?

[johanandren]

Ok, verified, it wasn't in the test kit in 2.4 that's why. Workaround would be to use the test kit one when building against 2.5, but that requires source changes and then it wouldn't work with 2.4.

[cchantep]

akka/akka#21028 (comment)

[cchantep]

Any news there? For now updating Akka Stream would need to remove .assertAllStagesStopped from test coverage (which is unfortonate, at least)