I am trying to test a Spring Cloud Streams and Kafka Streams application using the provided TestSupportBinder. The example provided in the docs works for me fine: https://docs.spring.io/spring-cloud-stream/docs/Fishtown.BUILD-SNAPSHOT/reference/htmlsingle/#_testing
However there is no example for a Kafka Streams application, and all the examples of testing Kafka Streams applications instead use the more heavyweight embedded Kafka instance integration test: https://github.com/spring-cloud/spring-cloud-stream-samples/tree/master/kafka-streams-samples
Even so, the recommendation for testing Spring Cloud Streams in general is to use the Test Binder: How to create unit test with kafka embedded in the spring cloud stream
This is what I want to do too, but specifically to test a Kafka Streams application. I do not want to go the embedded Kafka integration test route just yet, and just need unit tests, preferably with broker mocked out via the Test Binder.
What I've tried so far:
First I started with the working example from the Test Binder docs, and tried simply replacing @EnableBinding(Processor.class) with @EnableBinding(KafkaStreamsProcessor.class) as below:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment= SpringBootTest.WebEnvironment.RANDOM_PORT)
public class ExampleTest {
@Autowired
private Processor processor;
@Autowired
private MessageCollector messageCollector;
@Test
@SuppressWarnings("unchecked")
public void testWiring() {
Message<String> message = new GenericMessage<>("hello");
processor.input().send(message);
Message<String> received = (Message<String>) messageCollector.forChannel(processor.output()).poll();
assertThat(received.getPayload(), equalTo("hello world"));
}
@SpringBootApplication
@EnableBinding(KafkaStreamsProcessor.class)
public static class MyProcessor {
@Autowired
private Processor channels;
@Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
public KStream<String, String> transform(KStream<String, String> in) {
return in.map((key, value) -> new KeyValue<>(key, value + " world"));
}
}
}
This results in NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.cloud.stream.messaging.Processor available:
java.lang.IllegalStateException: Failed to load ApplicationContext
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:125) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:107) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:117) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener.prepareTestInstance(SpringBootDependencyInjectionTestExecutionListener.java:44) ~[spring-boot-test-autoconfigure-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:242) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:227) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:246) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206) [.cp/:na]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'exampleTest.MyProcessor': Unsatisfied dependency expressed through field 'channels'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.cloud.stream.messaging.Processor' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:587) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:373) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1344) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:752) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:388) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:138) ~[spring-boot-test-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:99) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:117) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
... 26 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.cloud.stream.messaging.Processor' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1509) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1065) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
... 45 common frames omitted
Second I tried specifying subbing in @EnableBinding({ Processor.class, KafkaStreamsProcessor.class }), but this resulted in Invalid bean definition with name 'output' defined in org.springframework.cloud.stream.binder.kafka.streams.annotations.KafkaStreamsProcessor: bean definition with this name already exists:
java.lang.IllegalStateException: Failed to load ApplicationContext
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:125) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:107) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:117) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener.prepareTestInstance(SpringBootDependencyInjectionTestExecutionListener.java:44) ~[spring-boot-test-autoconfigure-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:242) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:227) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:246) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190) [spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460) [.cp/:na]
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206) [.cp/:na]
Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'output' defined in org.springframework.cloud.stream.binder.kafka.streams.annotations.KafkaStreamsProcessor: bean definition with this name already exists - Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.cloud.stream.messaging.Processor; factoryMethodName=output; initMethodName=null; destroyMethodName=null
at org.springframework.cloud.stream.binding.BindingBeanDefinitionRegistryUtils.registerBindingTargetBeanDefinition(BindingBeanDefinitionRegistryUtils.java:64) ~[spring-cloud-stream-2.1.0.BUILD-SNAPSHOT.jar:2.1.0.BUILD-SNAPSHOT]
at org.springframework.cloud.stream.binding.BindingBeanDefinitionRegistryUtils.registerOutputBindingTargetBeanDefinition(BindingBeanDefinitionRegistryUtils.java:54) ~[spring-cloud-stream-2.1.0.BUILD-SNAPSHOT.jar:2.1.0.BUILD-SNAPSHOT]
at org.springframework.cloud.stream.binding.BindingBeanDefinitionRegistryUtils.lambda$registerBindingTargetBeanDefinitions$0(BindingBeanDefinitionRegistryUtils.java:86) ~[spring-cloud-stream-2.1.0.BUILD-SNAPSHOT.jar:2.1.0.BUILD-SNAPSHOT]
at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:562) ~[spring-core-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:541) ~[spring-core-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.cloud.stream.binding.BindingBeanDefinitionRegistryUtils.registerBindingTargetBeanDefinitions(BindingBeanDefinitionRegistryUtils.java:76) ~[spring-cloud-stream-2.1.0.BUILD-SNAPSHOT.jar:2.1.0.BUILD-SNAPSHOT]
at org.springframework.cloud.stream.config.BindingBeansRegistrar.registerBeanDefinitions(BindingBeansRegistrar.java:45) ~[spring-cloud-stream-2.1.0.BUILD-SNAPSHOT.jar:2.1.0.BUILD-SNAPSHOT]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.lambda$loadBeanDefinitionsFromRegistrars$0(ConfigurationClassBeanDefinitionReader.java:360) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_161]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsFromRegistrars(ConfigurationClassBeanDefinitionReader.java:359) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:144) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:117) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:328) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:233) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:273) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:93) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:693) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:531) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:752) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:388) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:138) ~[spring-boot-test-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:99) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:117) ~[spring-test-5.0.4.RELEASE.jar:5.0.4.RELEASE]
... 26 common frames omitted
Third I tried @EnableBinding(KafkaStreamsProcessor.class) again, and replaced the declaration private Processor processor; with private KafkaStreamsProcessor processor;, but this results in compile errors because this interface does not define the method signatures the Test Binder tests use e.g processor.input().
Is what I'm trying to do possible, or are the embedded Kafka integration tests the only way to go with Spring Cloud Stream and Kafka Streams applications?
