add fusing

akka-stream-tests/src/test/scala/akka/stream/FusingSpec.scala

@@ -0,0 +1,40 @@
+/**
+ * Copyright (C) 2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.stream
+
+import akka.stream._
+import akka.stream.scaladsl._
+import akka.stream.testkit.AkkaSpec
+import org.scalactic.ConversionCheckedTripleEquals
+
+class FusingSpec extends AkkaSpec with ConversionCheckedTripleEquals {
+
+  implicit val materializer = ActorMaterializer()
+
+  "Fusing" must {
+
+    "fuse a moderately complex graph" in {
+      val g = Source.unfoldInf(1)(x ⇒ (x, x)).filter(_ % 2 == 1).alsoTo(Sink.fold(0)(_ + _)).to(Sink.fold(1)(_ + _))
+      val fused = Fusing.aggressive(g)
+      val module = fused.module
+      module.subModules.size should ===(1)
+      module.info.downstreams.size should be > 5
+      module.info.upstreams.size should be > 5
+    }
+
+    "not fuse across AsyncBoundary" in {
+      val g =
+        Source.unfoldInf(1)(x ⇒ (x, x)).filter(_ % 2 == 1)
+          .alsoTo(Sink.fold(0)(_ + (_: Int)).addAttributes(Attributes.asyncBoundary))
+          .to(Sink.fold(1)(_ + _))
+      val fused = Fusing.aggressive(g)
+      val module = fused.module
+      module.subModules.size should ===(2)
+      module.info.downstreams.size should be > 5
+      module.info.upstreams.size should be > 5
+    }
+
+  }
+
+}