Docs on fromSinkAndSource #25468 (#28349)

akka-docs/src/test/scala/docs/stream/operators/flow/FromSinkAndSource.scala

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2009-2019 Lightbend Inc. <https://www.lightbend.com>
+ */
+
+package docs.stream.operators.flow
+
+import akka.NotUsed
+import akka.actor.ActorSystem
+import akka.stream.scaladsl.BroadcastHub
+import akka.stream.scaladsl.Flow
+import akka.stream.scaladsl.Framing
+import akka.stream.scaladsl.Keep
+import akka.stream.scaladsl.MergeHub
+import akka.stream.scaladsl.Sink
+import akka.stream.scaladsl.Source
+import akka.stream.scaladsl.Tcp
+import akka.stream.testkit.TestPublisher
+import akka.stream.testkit.TestSubscriber
+import akka.stream.testkit.Utils.TE
+import akka.stream.testkit.scaladsl.TestSource
+import akka.stream.testkit.scaladsl.TestSink
+import akka.util.ByteString
+
+import scala.concurrent.duration._
+
+object FromSinkAndSource {
+
+  implicit val system: ActorSystem = ???
+
+  def halfClosedTcpServer(): Unit = {
+    // #halfClosedTcpServer
+    // close in immediately
+    val sink = Sink.cancelled[ByteString]
+    // periodic tick out
+    val source =
+      Source.tick(1.second, 1.second, "tick").map(_ => ByteString(System.currentTimeMillis().toString + "\n"))
+
+    val serverFlow = Flow.fromSinkAndSource(sink, source)
+
+    Tcp().bind("127.0.0.1", 9999).runForeach { incomingConnection =>
+      incomingConnection.handleWith(serverFlow)
+    }
+    // #halfClosedTcpServer
+  }
+
+  def chat(): Unit = {
+    // #chat
+    val (sink, source) = MergeHub.source[String].toMat(BroadcastHub.sink[String])(Keep.both).run()
+
+    val framing = Framing.delimiter(ByteString("\n"), 1024)
+
+    val sinkWithFraming = framing.map(bytes => bytes.utf8String).to(sink)
+    val sourceWithFraming = source.map(text => ByteString(text + "\n"))
+
+    val serverFlow = Flow.fromSinkAndSource(sinkWithFraming, sourceWithFraming)
+
+    Tcp().bind("127.0.0.1", 9999).runForeach { incomingConnection =>
+      incomingConnection.handleWith(serverFlow)
+    }
+    // #chat
+  }
+
+  def testing(): Unit = {
+    def myApiThatTakesAFlow[In, Out](flow: Flow[In, Out, NotUsed]): Unit = ???
+    // #testing
+    val inProbe = TestSubscriber.probe[String]
+    val outProbe = TestPublisher.probe[String]()
+    val testFlow = Flow.fromSinkAndSource(Sink.fromSubscriber(inProbe), Source.fromPublisher(outProbe))
+
+    myApiThatTakesAFlow(testFlow)
+    inProbe.expectNext("first")
+    outProbe.expectRequest()
+    outProbe.sendError(new RuntimeException("test error"))
+    // ...
+    // #testing
+  }
+}