GH-1617 added support for Flux<Message> functions to FunctionInvoker

Resolves #1617

spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/FunctionInvoker.java

@@ -169,7 +169,8 @@ class FunctionInvoker<I, O> implements Function<Flux<Message<I>>, Flux<Message<O
 		}
 		else {
 			returnMessage = (Message<O>) (value instanceof Message ? value
-					: this.messageConverter.toMessage(value, originalMessage.getHeaders()));
+					: this.messageConverter.toMessage(value,
+							originalMessage.getHeaders()));
 			if (returnMessage == null
 					&& value.getClass().isAssignableFrom(this.outputClass)) {
 				returnMessage = wrapOutputToMessage(value, originalMessage);
@@ -212,7 +213,11 @@ class FunctionInvoker<I, O> implements Function<Flux<Message<I>>, Flux<Message<O
 				? this.messageConverter.fromMessage(message, this.inputClass) : message);
 		Assert.notNull(argument, "Failed to resolve argument type '" + this.inputClass
 				+ "' from message: " + message);
-		if (!this.isInputArgumentMessage && argument instanceof Message) {
+		if (this.isInputArgumentMessage && !(argument instanceof Message)) {
+			argument = (T) MessageBuilder.withPayload(argument)
+					.copyHeaders(message.getHeaders()).build();
+		}
+		else if (!this.isInputArgumentMessage && argument instanceof Message) {
 			argument = ((Message<T>) argument).getPayload();
 		}
 		return argument;

spring-cloud-stream/src/test/java/org/springframework/cloud/stream/function/FunctionInvokerTests.java

@@ -49,7 +49,6 @@ import org.springframework.util.ReflectionUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-
 /**
  * @author Oleg Zhurakousky
  * @author Tolga Kavukcu
@@ -63,7 +62,30 @@ public class FunctionInvokerTests {
 	public void testSimpleEchoConfiguration() {
 		try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
 				TestChannelBinderConfiguration.getCompleteConfiguration(
-						SimpleEchoConfiguration.class))
+						SimpleEchoConfiguration.class)).web(WebApplicationType.NONE).run(
+								"--spring.jmx.enabled=false",
+								"--spring.cloud.stream.function.definition=func")) {
+
+			InputDestination inputDestination = context.getBean(InputDestination.class);
+			OutputDestination outputDestination = context
+					.getBean(OutputDestination.class);
+
+			Message<byte[]> inputMessage = MessageBuilder
+					.withPayload("{\"name\":\"bob\"}".getBytes()).build();
+			inputDestination.send(inputMessage);
+
+			Message<byte[]> outputMessage = outputDestination.receive();
+			assertThat(outputMessage.getPayload())
+					.isEqualTo("{\"name\":\"bob\"}".getBytes());
+
+		}
+	}
+
+	@Test
+	public void testFluxPojoFunction() {
+		try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
+				TestChannelBinderConfiguration
+						.getCompleteConfiguration(SimpleFluxFunctionConfiguration.class))
 								.web(WebApplicationType.NONE)
 								.run("--spring.jmx.enabled=false",
 										"--spring.cloud.stream.function.definition=func")) {
@@ -77,12 +99,33 @@ public class FunctionInvokerTests {
 			inputDestination.send(inputMessage);
 
 			Message<byte[]> outputMessage = outputDestination.receive();
-			System.out.println("Received: " + new String(outputMessage.getPayload()));
-			assertThat(outputMessage.getPayload()).isEqualTo("{\"name\":\"bob\"}".getBytes());
+			assertThat(outputMessage.getPayload()).isEqualTo("Person: bob".getBytes());
 
 		}
 	}
 
+	@Test
+	public void testFluxMessagePojoFunction() {
+		try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
+				TestChannelBinderConfiguration.getCompleteConfiguration(
+						SimpleFluxMessageFunctionConfiguration.class))
+								.web(WebApplicationType.NONE)
+								.run("--spring.jmx.enabled=false",
+										"--spring.cloud.stream.function.definition=func")) {
+
+			InputDestination inputDestination = context.getBean(InputDestination.class);
+			OutputDestination outputDestination = context
+					.getBean(OutputDestination.class);
+
+			Message<byte[]> inputMessage = MessageBuilder
+					.withPayload("{\"name\":\"bob\"}".getBytes()).build();
+			inputDestination.send(inputMessage);
+
+			Message<byte[]> outputMessage = outputDestination.receive();
+			assertThat(outputMessage.getPayload()).isEqualTo("Person: bob".getBytes());
+		}
+	}
+
 	@Test
 	public void testFunctionHonorsOutboundBindingContentType() {
 		try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
@@ -339,6 +382,7 @@ public class FunctionInvokerTests {
 		}
 
 		public static class Person {
+
 			private String name;
 
 			public String getName() {
@@ -348,7 +392,72 @@ public class FunctionInvokerTests {
 			public void setName(String name) {
 				this.name = name;
 			}
+
 		}
+
+	}
+
+	@EnableAutoConfiguration
+	@EnableBinding(Processor.class)
+	public static class SimpleFluxFunctionConfiguration {
+
+		@Bean
+		public Function<Flux<Person>, Flux<String>> func() {
+			return x -> x.map(person -> person.toString());
+		}
+
+		public static class Person {
+
+			private String name;
+
+			public String getName() {
+				return name;
+			}
+
+			public void setName(String name) {
+				this.name = name;
+			}
+
+			public String toString() {
+				return "Person: " + name;
+			}
+
+		}
+
+	}
+
+	@EnableAutoConfiguration
+	@EnableBinding(Processor.class)
+	public static class SimpleFluxMessageFunctionConfiguration {
+
+		@Bean
+		public Function<Flux<Message<Person>>, Flux<Message<String>>> func() {
+			return x -> x.map(personMessage -> {
+				Person person = personMessage.getPayload();
+				Message<String> message = MessageBuilder.withPayload(person.toString())
+						.copyHeaders(personMessage.getHeaders()).build();
+				return message;
+			});
+		}
+
+		public static class Person {
+
+			private String name;
+
+			public String getName() {
+				return name;
+			}
+
+			public void setName(String name) {
+				this.name = name;
+			}
+
+			public String toString() {
+				return "Person: " + name;
+			}
+
+		}
+
 	}
 
 	@EnableAutoConfiguration