Hi, While working on an integration test <https://github.com/apache/beam/pull/5347> for Pubsub-related functionality I couldn't find a good solution to test the pipelines that don't reliably stop.
I propose we extend PAssert to support eventual verification. In this case some success/failure predicate is being constantly evaluated against all elements of the pipeline until it's met. At that point the result gets communicated to the main program/test. Example API: *PAssert .thatEventually(pcollection) .containsInAnyOrder(e1, e2, e3) .synchronizingOver(signalOverPubsub()); .timeoutAfter(10 min)* Details doc <https://docs.google.com/document/d/1X_3KH_6QyfOSnh5kNK-fHlkEDrwPVpA2RnRggMMxhUk/edit#heading=h.i3owzq4bs63l> Comments, thoughts, things that I missed? Regards, Anton
