Spring Cloud Stream unit test Producer - spring-cloud

Question

I'm using Spring Cloud Stream 3.1.3.
I'm migrate from a pre 3.1 version, so I wrote my producer using a java.util.Function (I know I can use Supplier but this is what I need)
application.yaml file is configured with function definition, input and output bindings, and this is what I have:
#EnableAutoConfiguration
#Service
public class Producer {
public void produce(int messageId, Object data) {
Message<Object> message = MessageBuilder
.withPayload(data)
.setHeader(PARTITION_KEY, messageId)
.build();
streamBridge.send("produceMessage-in-0", message);
}
#Bean
public Function<Message<Object>, Message<Object>> produceMessage() {
return (input) -> {
int messageId = input.getHeaders().get(PARTITION_KEY, Integer.class);
Object message = input.getPayload();
return MessageBuilder
.withPayload(message)
.setHeader(MessageHeaders.CONTENT_TYPE, MimeTypeUtils.APPLICATION_JSON)
.setHeader(PARTITION_KEY, messageId)
.setHeader("type", "MyMessage")
.build();
};
}
}
Now, I would like to test this implmentation, so I wrote this test class
#SpringBootTest
class ProducerTest {
#Autowired
private Producer producer;
#Autowired
private ObjectMapper objectMapper;
#Test
void produceOk() {
try (ConfigurableApplicationContext context = new SpringApplicationBuilder(TestChannelBinderConfiguration.getCompleteConfiguration(Producer.class)).run()) {
producer.produce(1, new MyMessage(1, "Hello"));
OutputDestination output = context.getBean(OutputDestination.class);
Message<byte[]> received = output.receive();
Assertions.assertNotNull(received);
}
}
}
Test fails because output.receive() returns null.
Is this the right way to test my code?
Thanks

Answer 1

It is difficult to see what your issue may be since we don't see the entire setup of your project, but here are few pointers that may help. . .
Please look at any of the tests we use in the framework as well as checkout the Testing section of the reference manual.
There is also s dedicated StreamBridgeTests.java which is what I believe you are looking for.