Play 2.1: Await result from enumerator - scala

Question

I'm working on testing my WebSocket code in Play Framework 2.1. My approach is to get the iterator/enumerator pair that are used for the actual web socket, and just test pushing data in and pulling data out.
Unfortunately, I just cannot figure out how to get data out of an Enumerator. Right now my code looks roughly like this:
val (in, out) = createClient(FakeRequest("GET", "/myendpoint"))
in.feed(Input.El("My input here"))
in.feed(Input.EOF)
//no idea how to get data from "out"
As far as I can tell, the only way to get data out of an enumerator is through an iteratee. But I can't figure out how to just wait until I get the full list of strings coming out of the enumerator. What I want is a List[String], not a Future[Iteratee[A,String]] or an Expectable[Iteratee[String]] or yet another Iteratee[String]. The documentation is confusing at best.
How do I do that?

Answer 1

You can consume an Enumerator like this:
val out = Enumerator("one", "two")
val consumer = Iteratee.getChunks[String]
val appliedEnumeratorFuture = out.apply(consumer)
val appliedEnumerator = Await.result(appliedEnumeratorFuture, 1.seconds)
val result = Await.result(appliedEnumerator.run, 1.seconds)
println(result) // List("one", "two")
Note that you need to await a Future twice because Enumerator and Iteratee control the speed of respectively producing and consuming values.
A more elaborate example for an Iteratee -> Enumerator chain where feeding the Iteratee results in the Enumerator producing values:
// create an enumerator to which messages can be pushed
// using a channel
val (out, channel) = Concurrent.broadcast[String]
// create the input stream. When it receives an string, it
// will push the info into the channel
val in =
Iteratee.foreach[String] { s =>
channel.push(s)
}.map(_ => channel.eofAndEnd())
// Instead of using the complex `feed` method, we just create
// an enumerator that we can use to feed the input stream
val producer = Enumerator("one", "two").andThen(Enumerator.eof)
// Apply the input stream to the producer (feed the input stream)
val producedElementsFuture = producer.apply(in)
// Create a consumer for the output stream
val consumer = Iteratee.getChunks[String]
// Apply the consumer to the output stream (consume the output stream)
val consumedOutputStreamFuture = out.apply(consumer)
// Await the construction of the input stream chain
Await.result(producedElementsFuture, 1.second)
// Await the construction of the output stream chain
val consumedOutputStream = Await.result(consumedOutputStreamFuture, 1.second)
// Await consuming the output stream
val result = Await.result(consumedOutputStream.run, 1.second)
println(result) // List("one", "two")