Rule 3.12 verification in subscriber whitebox now really checks it

This verification is now moved to PublisherVerification, as it's a
publishers behavior (*it* must stop emiting, not the subscriber).

Resolves reactive-streams#115

Author: ktoso

tck/src/main/java/org/reactivestreams/tck/IdentityProcessorVerification.java

@@ -324,6 +324,11 @@ public void spec309_requestNegativeNumberMustThrowIllegalArgumentException() thr
     publisherVerification.spec309_requestNegativeNumberMustThrowIllegalArgumentException();
   }
 
+  @Test
+  public void spec312_cancelMustMakeThePublisherToEventuallyStopSignaling() throws Throwable {
+    publisherVerification.spec312_cancelMustMakeThePublisherToEventuallyStopSignaling();
+  }
+
   @Test
   public void spec313_cancelMustMakeThePublisherEventuallyDropAllReferencesToTheSubscriber() throws Throwable {
     publisherVerification.spec313_cancelMustMakeThePublisherEventuallyDropAllReferencesToTheSubscriber();
@@ -386,9 +391,6 @@ public void onSubscribe(final Subscription subscription) {
             if (subs.isCompleted()) subscription.cancel(); // the Probe must also pass subscriber verification
 
             probe.registerOnSubscribe(new SubscriberWhiteboxVerification.SubscriberPuppet() {
-              public void triggerShutdown() {
-                subscription.cancel();
-              }
 
               @Override
               public void triggerRequest(long elements) {
@@ -583,11 +585,6 @@ public void spec311_requestMaySynchronouslyCallOnCompleteOrOnError() throws Exce
     subscriberVerification.spec311_requestMaySynchronouslyCallOnCompleteOrOnError();
   }
 
-  @Test
-  public void spec312_cancelMustRequestThePublisherToEventuallyStopSignaling() throws Throwable {
-    subscriberVerification.spec312_cancelMustRequestThePublisherToEventuallyStopSignaling();
-  }
-
   @Test
   public void spec314_cancelMayCauseThePublisherToShutdownIfNoOtherSubscriptionExists() throws Exception {
     subscriberVerification.spec314_cancelMayCauseThePublisherToShutdownIfNoOtherSubscriptionExists();

tck/src/main/java/org/reactivestreams/tck/PublisherVerification.java

@@ -656,6 +656,48 @@ public void run() {
     });
   }
 
+  // Verifies rule: https://github.com/reactive-streams/reactive-streams#3.12
+  @Required @Test
+  public void spec312_cancelMustMakeThePublisherToEventuallyStopSignaling() throws Throwable {
+    final int elementsCount = 20;
+
+    activePublisherTest(elementsCount, new PublisherTestRun<T>() {
+      @Override
+      public void run(Publisher<T> pub) throws Throwable {
+        final ManualSubscriber<T> sub = env.newManualSubscriber(pub);
+
+        sub.request(10);
+        sub.request(5);
+        final int totalDemand = 10 + 5;
+
+        sub.cancel(); // must keep subscription so we may accept
+
+        sub.nextElement();
+        int onNextSignals = 1;
+
+        boolean stillBeingSignalled;
+        do {
+          try {
+            sub.expectNone();
+            env.verifyNoAsyncErrors();
+
+            stillBeingSignalled = false;
+          } catch (Throwable th) {
+            onNextSignals += 1;
+            env.dropAsyncError();
+
+            stillBeingSignalled = true;
+          }
+        } while (stillBeingSignalled && onNextSignals < elementsCount);
+
+        assertTrue(onNextSignals <= totalDemand,
+          String.format("Publisher signalled [%d] elements, which is more than the signalled demand: %d", onNextSignals, totalDemand));
+      }
+    });
+
+    env.verifyNoAsyncErrors();
+  }
+
   // Verifies rule: https://github.com/reactive-streams/reactive-streams#3.13
   @Required @Test
   public void spec313_cancelMustMakeThePublisherEventuallyDropAllReferencesToTheSubscriber() throws Throwable {

tck/src/main/java/org/reactivestreams/tck/SubscriberBlackboxVerification.java

@@ -335,12 +335,6 @@ public void spec311_blackbox_requestMaySynchronouslyCallOnCompleteOrOnError() th
     notVerified(); // cannot be meaningfully tested, or can it?
   }
 
-  // Verifies rule: https://github.com/reactive-streams/reactive-streams#3.12
-  @Required @Test
-  public void spec312_blackbox_cancelMustRequestThePublisherToEventuallyStopSignaling() throws Throwable {
-    notVerified(); // cannot be meaningfully tested as black box, or can it?
-  }
-
   // Verifies rule: https://github.com/reactive-streams/reactive-streams#3.14
   @NotVerified @Test
   public void spec314_blackbox_cancelMayCauseThePublisherToShutdownIfNoOtherSubscriptionExists() throws Exception {

tck/src/main/java/org/reactivestreams/tck/SubscriberWhiteboxVerification.java

@@ -52,6 +52,17 @@ protected SubscriberWhiteboxVerification(TestEnvironment env) {
    */
   public abstract Publisher<T> createHelperPublisher(long elements);
 
+  /**
+   * Used to break possibly infinite wait-loops.
+   * Some Rules use the "eventually stop signalling" wording, which requires the test to spin accepting {@code onNext}
+   * signals until no more are signalled. In these tests, this value will be used as upper bound on the number of spin iterations.
+   *
+   * Override this method in case your implementation synchronously signals very large batches before reacting to cancellation (for example).
+   */
+  public long maxOnNextSignalsInTest() {
+    return 100;
+  }
+
   ////////////////////// TEST ENV CLEANUP /////////////////////////////////////
 
   @BeforeMethod
@@ -431,20 +442,6 @@ public void spec311_requestMaySynchronouslyCallOnCompleteOrOnError() throws Exce
     notVerified(); // cannot be meaningfully tested, or can it?
   }
 
-  // Verifies rule: https://github.com/reactive-streams/reactive-streams#3.12
-  @Required @Test
-  public void spec312_cancelMustRequestThePublisherToEventuallyStopSignaling() throws Throwable {
-    subscriberTest(new TestStageTestRun() {
-      @Override
-      public void run(WhiteboxTestStage stage) throws InterruptedException {
-        stage.puppet().signalCancel();
-        stage.expectCancelling();
-
-        stage.verifyNoAsyncErrors();
-      }
-    });
-  }
-
   // Verifies rule: https://github.com/reactive-streams/reactive-streams#3.14
   @NotVerified @Test
   public void spec314_cancelMayCauseThePublisherToShutdownIfNoOtherSubscriptionExists() throws Exception {
@@ -518,7 +515,7 @@ public void subscriberTestWithoutSetup(TestStageTestRun body) throws Throwable {
 
   public class WhiteboxTestStage extends ManualPublisher<T> {
     public Publisher<T> pub;
-    public ManualSubscriber<T> tees; // gives us access to an infinite stream of T values
+    public ManualSubscriber<T> tees; // gives us access to a stream T values
     public WhiteboxSubscriberProbe<T> probe;
 
     public T lastT = null;
@@ -546,6 +543,10 @@ public SubscriberPuppet puppet() {
       return probe.puppet();
     }
 
+    public WhiteboxSubscriberProbe<T> probe() {
+      return probe;
+    }
+
     public Publisher<T> createHelperPublisher(long elements) {
       return SubscriberWhiteboxVerification.this.createHelperPublisher(elements);
     }

tck/src/main/java/org/reactivestreams/tck/TestEnvironment.java

@@ -128,6 +128,10 @@ public void clearAsyncErrors() {
     asyncErrors.clear();
   }
 
+  public void dropAsyncError() {
+    asyncErrors.remove(0);
+  }
+
   public void verifyNoAsyncErrors(long delay) {
     try {
       Thread.sleep(delay);
@@ -620,7 +624,6 @@ public boolean isCompleted() {
       return _value != null;
     }
 
-
     /**
      * Allows using expectCompletion to await for completion of the value and complete it _then_
      */
@@ -761,7 +764,7 @@ public void expectError(long timeoutMillis, String errorMsg) throws Exception {
       }
     }
 
-    void expectNone(long withinMillis, String errorMsgPrefix) throws InterruptedException {
+    public void expectNone(long withinMillis, String errorMsgPrefix) throws InterruptedException {
       Thread.sleep(withinMillis);
       Optional<T> value = abq.poll();