+doc #15239: Stream cookbook

akka-docs-dev/rst/scala/code/docs/stream/cookbook/RecipeMissedTicks.scala

@@ -0,0 +1,53 @@
+package docs.stream.cookbook
+
+import akka.stream.scaladsl.{ Sink, Source }
+import akka.stream.testkit.StreamTestKit
+import akka.stream.testkit.StreamTestKit.{ SubscriberProbe, PublisherProbe }
+
+import scala.concurrent.duration._
+
+class RecipeMissedTicks extends RecipeSpec {
+
+  "Recipe for collecting missed ticks" must {
+
+    "work" in {
+      type Tick = Unit
+
+      val pub = PublisherProbe[Tick]()
+      val sub = SubscriberProbe[Int]()
+      val tickStream = Source(pub)
+      val sink = Sink(sub)
+
+      //#missed-ticks
+      // tickStream is a Source[Tick]
+      val missedTicks: Source[Int] =
+        tickStream.conflate(seed = (_) => 0)(
+          (missedTicks, tick) => missedTicks + 1)
+      //#missed-ticks
+
+      missedTicks.to(sink).run()
+      val manualSource = new StreamTestKit.AutoPublisher(pub)
+
+      manualSource.sendNext(())
+      manualSource.sendNext(())
+      manualSource.sendNext(())
+      manualSource.sendNext(())
+
+      val subscription = sub.expectSubscription()
+      subscription.request(1)
+      sub.expectNext(3)
+
+      subscription.request(1)
+      sub.expectNoMsg(100.millis)
+
+      manualSource.sendNext(())
+      sub.expectNext(0)
+
+      manualSource.sendComplete()
+      subscription.request(1)
+      sub.expectComplete()
+    }
+
+  }
+
+}