test stream-rabbitmq occurs an error: Dispatcher has no subscribers for channel

Question

I code a test class for using spring-cloud-starter-stream-rabbit, when I only run receiver, and send a message from rabbitmq, it works; but when I run the test sender class, it occurs an error: org.springframework.messaging.MessageDeliveryException: Dispatcher has no subscribers for channel, what should I do to make it correct?

My step:

First, run SpringbootApplication Second, run JUnit test

spring-boot-starter-parent 2.1.3.RELEASE JDK8 rabbitmq utf8

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.springcloud</groupId>
    <artifactId>stream-hello</artifactId>
    <version>1.0</version>
    <name>stream-hello</name>
    <description>SpringCloud Project</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-stream-rabbit</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

SinkReceiver.java

@EnableBinding({Sink.class})
public class SinkReceiver {
    private static Logger logger = LoggerFactory.getLogger(SinkReceiver.class);

    @StreamListener(Sink.INPUT)
    public void receive(Object payload) {
        logger.info("Received: " + payload);
    }

}

StreamHelloApplication.java

@SpringBootApplication
public class StreamHelloApplication {
    public static void main(String[] args) {
        SpringApplication.run(StreamHelloApplication.class, args);
    }
}

StreamHelloApplicationTests.java

@RunWith(SpringRunner.class)
@EnableBinding(value = {StreamHelloApplicationTests.SinkSender.class})
public class StreamHelloApplicationTests {

    @Autowired
    private SinkSender sinkSender;

    @Test
    public void sinkSenderTester() {
        sinkSender.output().send(MessageBuilder.withPayload("produce a message : sinkSenderTest").build());
    }

    public interface SinkSender {
        String OUTPUT = "input";

        @Output(SinkSender.OUTPUT)
        MessageChannel output();
    }

}

application.properties

spring.application.name=stream-hello

#config rabbitmq
spring.rabbitmq.host=localhost
spring.rabbitmq.port=35672
spring.rabbitmq.username=admin
spring.rabbitmq.password=123456

I expect the junit test can run successful, but it run occurs error. stack trace like follow:

org.springframework.messaging.MessageDeliveryException: Dispatcher has no subscribers for channel 'org.springframework.context.support.GenericApplicationContext@68ceda24.input'.; nested exception is org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers, failedMessage=GenericMessage [payload=byte[34], headers={contentType=application/json, id=fc0a6890-4945-142b-55cd-668b0d3f22ed, timestamp=1555817595975}], failedMessage=GenericMessage [payload=byte[34], headers={contentType=application/json, id=fc0a6890-4945-142b-55cd-668b0d3f22ed, timestamp=1555817595975}]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:77)
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:461)
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:401)
    at com.springcloud.StreamHelloApplicationTests.sinkSenderTester(StreamHelloApplicationTests.java:21)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
Caused by: org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers, failedMessage=GenericMessage [payload=byte[34], headers={contentType=application/json, id=fc0a6890-4945-142b-55cd-668b0d3f22ed, timestamp=1555817595975}]
    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)
    ... 34 more

Answer 1

Your binding interface SinkSender is not bound to anything. The "input" channel is created but there is no subscriber. And your SinkReceiver is not even part of the test. For testing please read the Testing of the user manual especially the new test binder. The above section contain full working samples as well.