void verify(@Nullable Throwable cause) {
            // Ensure subscription.cancel() has been invoked.
            Mockito.verify(subscription, timeout(3000)).cancel();

            // Ensure completionFuture is complete exceptionally.
            assertThat(publisher.whenComplete()).isCompletedExceptionally();
            if (cause == null) {
                assertThatThrownBy(() -> publisher.whenComplete().get())
                        .hasCauseExactlyInstanceOf(AbortedStreamException.class);
            } else {
                assertThatThrownBy(() -> publisher.whenComplete().get())
                        .hasCauseExactlyInstanceOf(cause.getClass());
            }
        }
Tests if {@link PublisherBasedStreamMessage#abort()} prohibits further subscription.
core/src/test/java/com/linecorp/armeria/common/stream/PublisherBasedStreamMessageTest.java