ensure that graph attributes are not lost

- this entails making Module.isSealed==true if attributes are set
- also removed Module.nest(), which implied fixing replaceShape to form
  a CompositeModule where CopiedModule was used before (GraphModule and
  TlsModule)

akka-stream-tests/src/test/resources/reference.conf

@@ -8,4 +8,5 @@ akka {
   akka.actor.warn-about-java-serializer-usage = false
 
   stream.materializer.debug.fuzzing-mode = on
+  stream.secret-test-fuzzing-warning-disable = 42
 }

akka-stream-tests/src/test/scala/akka/stream/impl/fusing/InterpreterSpec.scala

@@ -511,7 +511,9 @@ class InterpreterSpec extends AkkaSpec with GraphInterpreterSpecKit {
       downstream.requestOne()
       lastEvents() should be(Set(RequestOne))
 
-      upstream.onComplete()
+      EventFilter[IllegalArgumentException](pattern = ".*Cannot pull closed port.*", occurrences = 1).intercept {
+        upstream.onComplete()
+      }
       val ev = lastEvents()
       ev.nonEmpty should be(true)
       ev.forall {

akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowIteratorSpec.scala

@@ -4,7 +4,6 @@
 package akka.stream.scaladsl
 
 import akka.NotUsed
-
 import scala.collection.immutable
 import scala.concurrent.duration._
 import akka.stream.ActorMaterializer
@@ -14,6 +13,7 @@ import akka.stream.testkit.Utils._
 import org.reactivestreams.Subscription
 import akka.testkit.TestProbe
 import org.reactivestreams.Subscriber
+import akka.testkit.EventFilter
 
 class FlowIteratorSpec extends AbstractFlowIteratorSpec {
   override def testName = "A Flow based on an iterator producing function"
@@ -40,7 +40,9 @@ class FlowIterableSpec extends AbstractFlowIteratorSpec {
     sub.request(1)
     c.expectNext(1)
     c.expectNoMsg(100.millis)
-    sub.request(2)
+    EventFilter[IllegalStateException](message = "not two", occurrences = 1).intercept {
+      sub.request(2)
+    }
     c.expectError().getMessage should be("not two")
     sub.request(2)
     c.expectNoMsg(100.millis)

akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowZipWithSpec.scala

@@ -6,6 +6,7 @@ package akka.stream.scaladsl
 import akka.stream.testkit.{ BaseTwoStreamsSetup, TestSubscriber }
 import org.reactivestreams.Publisher
 import scala.concurrent.duration._
+import akka.testkit.EventFilter
 
 class FlowZipWithSpec extends BaseTwoStreamsSetup {
 
@@ -46,7 +47,9 @@ class FlowZipWithSpec extends BaseTwoStreamsSetup {
       probe.expectNext(1 / -2)
       probe.expectNext(2 / -1)
 
-      subscription.request(2)
+      EventFilter[ArithmeticException](occurrences = 1).intercept {
+        subscription.request(2)
+      }
       probe.expectError() match {
         case a: java.lang.ArithmeticException ⇒ a.getMessage should be("/ by zero")
       }

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphUnzipWithSpec.scala

@@ -8,9 +8,9 @@ import akka.stream.testkit.TestSubscriber.Probe
 import akka.stream.testkit.Utils._
 import akka.stream.testkit._
 import org.reactivestreams.Publisher
-
 import scala.concurrent.duration._
 import scala.util.control.NoStackTrace
+import akka.testkit.EventFilter
 
 class GraphUnzipWithSpec extends AkkaSpec {
 
@@ -174,7 +174,9 @@ class GraphUnzipWithSpec extends AkkaSpec {
       leftProbe.expectNext(1 / -1)
       rightProbe.expectNext("1/-1")
 
-      requestFromBoth()
+      EventFilter[ArithmeticException](occurrences = 1).intercept {
+        requestFromBoth()
+      }
 
       leftProbe.expectError() match {
         case a: java.lang.ArithmeticException ⇒ a.getMessage should be("/ by zero")

akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphZipWithSpec.scala

@@ -3,6 +3,7 @@ package akka.stream.scaladsl
 import akka.stream.testkit._
 import scala.concurrent.duration._
 import akka.stream._
+import akka.testkit.EventFilter
 
 class GraphZipWithSpec extends TwoStreamsSetup {
   import GraphDSL.Implicits._
@@ -65,7 +66,9 @@ class GraphZipWithSpec extends TwoStreamsSetup {
       probe.expectNext(1 / -2)
       probe.expectNext(2 / -1)
 
-      subscription.request(2)
+      EventFilter[ArithmeticException](occurrences = 1).intercept {
+        subscription.request(2)
+      }
       probe.expectError() match {
         case a: java.lang.ArithmeticException ⇒ a.getMessage should be("/ by zero")
       }

akka-stream-tests/src/test/scala/akka/stream/scaladsl/SourceSpec.scala

@@ -13,6 +13,7 @@ import scala.util.control.NoStackTrace
 import akka.stream._
 import akka.stream.testkit._
 import akka.NotUsed
+import akka.testkit.EventFilter
 
 class SourceSpec extends AkkaSpec with DefaultTimeout with ScalaFutures {
 
@@ -235,13 +236,14 @@ class SourceSpec extends AkkaSpec with DefaultTimeout with ScalaFutures {
 
     "terminate with a failure if there is an exception thrown" in {
       val t = new RuntimeException("expected")
-      whenReady(
-        Source.unfold((0, 1)) {
-          case (a, _) if a > 10000000 ⇒ throw t
-          case (a, b)                 ⇒ Some((b, a + b) → a)
-        }.runFold(List.empty[Int]) { case (xs, x) ⇒ x :: xs }.failed) {
-          _ should be theSameInstanceAs (t)
-        }
+      EventFilter[RuntimeException](message = "expected", occurrences = 1) intercept
+        whenReady(
+          Source.unfold((0, 1)) {
+            case (a, _) if a > 10000000 ⇒ throw t
+            case (a, b)                 ⇒ Some((b, a + b) → a)
+          }.runFold(List.empty[Int]) { case (xs, x) ⇒ x :: xs }.failed) {
+            _ should be theSameInstanceAs (t)
+          }
     }
 
     "generate a finite fibonacci sequence asynchronously" in {