用他们的test-binder测试spring-cloud-stream总是会抛出MessageDeliveryException。Dispatcher没有通道的订阅者。

Question

我正试图为我的消息生产者编写测试。但每当我尝试使用注入的Bindings发送消息时，我都会得到以下的错误信息。

Caused by: org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers, failedMessage=GenericMessage [payload=..., headers={spanTraceId=0761b2d61b665041, spanId=e3b298682fefe198, spanParentSpanId=549ea87126d2484d, nativeHeaders={X-B3-TraceId=[0761b2d61b665041], spanTraceId=[0761b2d61b665041], X-B3-SpanId=[e3b298682fefe198], spanId=[e3b298682fefe198], X-B3-ParentSpanId=[549ea87126d2484d], spanParentSpanId=[549ea87126d2484d], X-B3-Sampled=[0], spanSampled=[0]}, X-B3-SpanId=e3b298682fefe198, X-B3-ParentSpanId=549ea87126d2484d, X-B3-Sampled=0, X-B3-TraceId=0761b2d61b665041, id=0c885a37-a1b1-fc0a-1314-e403ec1bffdb, spanSampled=0, contentType=application/json, timestamp=1589551815143}]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:138)
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:105)
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73)
    ... 42 more

因为我测试的是消息生产者，所以我的代码中自然没有消费者。我怎样才能解决这个异常？

这里是我创建的一个最小的测试类，显示了同样的行为。

@RunWith(SpringRunner.class)
@ActiveProfiles("test")
@SpringBootTest(classes = {MessagingTest.SampleConfiguration.class, Application.class, EventMockConfiguration.class})
public class MessagingTest {

    @Autowired
    private LibraryMessageSource libraryMessageSource;

    @Autowired
    private InputDestination input;

    @Autowired
    private OutputDestination output;

    @Test
    public void test() throws Exception {
        libraryMessageSource.creations().send(MessageBuilder.withPayload("test").build());
    }

    @SpringBootApplication
    @Import({TestChannelBinderConfiguration.class})
    public static class SampleConfiguration {

    }
}

注：Application.class是我的应用程序的主类，EventMock用一个特定的mock覆盖了上下文中的bean。

public interface LibraryMessageSource {

    String LIBRARY_CREATE = "messages-library-create";
    String LIBRARY_UPDATE = "messages-library-update";

    @Input(LIBRARY_CREATE)
    MessageChannel creations();

    @Input(LIBRARY_UPDATE)
    MessageChannel updates();
}

Answer 1

由于我正在测试消息生产者

你的应用程序有一个消费者，而不是生产者

    @Input(INPUT)
    MessageChannel events();

而你却没有 @StreamListener 认购了它。

    @Test
    public void test() throws Exception {
        libraryMessageSource.events().send(MessageBuilder.withPayload("test").build());
    }