Enhance testing utilities

context-propagation/src/test/java/io/smallrye/mutiny/context/MultiContextPropagationTest.java

@@ -252,7 +252,7 @@ public void testOnSubscribe() {
                 })
                 .subscribe().withSubscriber(AssertSubscriber.create(20));
 
-        subscriber.await()
+        subscriber.awaitCompletion()
                 .assertItems(0L, 1L, 2L, 3L, 4L);
 
     }
@@ -270,7 +270,7 @@ public void testSelectWhere() {
                 })
                 .subscribe().withSubscriber(AssertSubscriber.create(20));
 
-        subscriber.await()
+        subscriber.awaitCompletion()
                 .assertItems(0L, 2L, 4L);
 
     }
@@ -289,8 +289,7 @@ public void testScan() {
                 .select().first(10)
                 .subscribe().withSubscriber(AssertSubscriber.create(10));
 
-        subscriber.await()
-                .assertCompleted()
+        subscriber.awaitCompletion()
                 .assertItems(0, 1, 3, 6, 10, 15, 21, 28, 36, 45);
 
     }

documentation/src/test/java/guides/operators/BroadcastProcessorTest.java

@@ -30,7 +30,6 @@ public void test() {
         // end::code[]
         AssertSubscriber<String> subscriber = AssertSubscriber.create(Long.MAX_VALUE);
         multi.subscribe().withSubscriber(subscriber)
-                .await()
-                .assertCompleted();
+                .awaitCompletion();
     }
 }

documentation/src/test/java/guides/operators/UnicastProcessorTest.java

@@ -28,7 +28,7 @@ public void test() {
         // end::code[]
         AssertSubscriber<String> subscriber = AssertSubscriber.create(Long.MAX_VALUE);
         multi.subscribe().withSubscriber(subscriber)
-                .await()
+                .awaitCompletion()
                 .run(() -> assertThat(subscriber.getItems()).hasSize(1000));
     }
 }

implementation/src/main/java/io/smallrye/mutiny/groups/UniOnFailure.java

@@ -121,7 +121,13 @@ public Uni<T> call(Function<Throwable, Uni<?>> action) {
             //noinspection unchecked
             return (Uni<T>) uni
                     .onItem().failWith(ignored -> failure)
-                    .onFailure().apply(subFailure -> new CompositeException(failure, subFailure));
+                    .onFailure().transform(subFailure -> {
+                        if (subFailure != failure) {
+                            return new CompositeException(failure, subFailure);
+                        } else {
+                            return subFailure;
+                        }
+                    });
         });
     }
 

implementation/src/main/java/io/smallrye/mutiny/helpers/spies/MultiOnCancellationSpy.java

@@ -23,4 +23,16 @@ public boolean isCancelled() {
     public String toString() {
         return "MultiOnCancellationSpy{} " + super.toString();
     }
+
+    public void assertCancelled() {
+        if (!isCancelled()) {
+            throw new AssertionError("Expected downstream cancellation, but it did not happen");
+        }
+    }
+
+    public void assertNotCancelled() {
+        if (isCancelled()) {
+            throw new AssertionError("Did not expect to receive a downstream cancellation");
+        }
+    }
 }