In unit tests, Consumer function does not work with Sleuth - ClassCastException

[julb]

Dear team,

I have written a simple Consumer.
The function works as expected when I execute it through the main class.

However, when I write a unit test for that function, I get a ClassCastException because of Sleuth:

java.lang.ClassCastException: class me.julb.library.dto.googlechat.GoogleChatMessageDTO cannot be cast to class org.springframework.messaging.Message (me.julb.library.dto.googlechat.GoogleChatMessageDTO and org.springframework.messaging.Message are in unnamed module of loader 'app')
 at org.springframework.cloud.sleuth.instrument.messaging.TraceFunctionAroundWrapper.doApply(TraceFunctionAroundWrapper.java:99)
 at org.springframework.cloud.function.context.catalog.FunctionAroundWrapper.apply(FunctionAroundWrapper.java:47)
 at org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry$1.doApply(SimpleFunctionRegistry.java:256)
 at org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry$FunctionInvocationWrapper.apply(SimpleFunctionRegistry.java:550)
 at org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry$FunctionInvocationWrapper.accept(SimpleFunctionRegistry.java:566)
 at me.julb.functions.SendGoogleChatFunctionTest.whenInvokingFunction_thenSendGoogleChat(SendGoogleChatFunctionTest.java:69)

From what I understand, it seems that the Sleuth TraceFunctionAroundWrapper is invoked before the input is converted to a Message in FunctionInvocationWrapper#convertInputIfNecessary.

I'm using :

• Spring Cloud Function 3.2.1
• Spring Cloud Sleuth 3.1.0.

Workarounds found:

1/ Transform the Consumer<GoogleChatMessageDTO> to a Consumer<Message<GoogleChatMessageDTO>>
2/ Set property spring.sleuth.function.enabled: false for unit tests

[marcingrzejszczak]

Can you show your unit test?

[julb]

Wow, that was fast!
Thanks a lot @marcingrzejszczak !

[davidmelia]

@marcingrzejszczak posted in the other discussion but this is till broken for me

I have updated my prototype https://github.com/davidmelia/spring-boot-webflux-avro-sink-only to 2021.0.1-SNAPSHOT and can confirm it's still broken :-(

java.lang.ClassCastException: class reactor.core.publisher.MonoPeekTerminal cannot be cast to class reactor.core.publisher.Flux (reactor.core.publisher.MonoPeekTerminal and reactor.core.publisher.Flux are in unnamed module of loader 'app')
   at org.springframework.cloud.sleuth.instrument.messaging.TraceFunctionAroundWrapper.reactorFluxStream(TraceFunctionAroundWrapper.java:204) ~[spring-cloud-sleuth-instrumentation-3.1.1-SNAPSHOT.jar:3.1.1-SNAPSHOT]
   at org.springframework.cloud.sleuth.instrument.messaging.TraceFunctionAroundWrapper.reactorStream(TraceFunctionAroundWrapper.java:137) ~[spring-cloud-sleuth-instrumentation-3.1.1-SNAPSHOT.jar:3.1.1-SNAPSHOT]
   at org.springframework.cloud.sleuth.instrument.messaging.TraceFunctionAroundWrapper.doApply(TraceFunctionAroundWrapper.java:102) ~[spring-cloud-sleuth-instrumentation-3.1.1-SNAPSHOT.jar:3.1.1-SNAPSHOT]
   at org.springframework.cloud.function.context.catalog.FunctionAroundWrapper.apply(FunctionAroundWrapper.java:47) ~[spring-cloud-function-context-3.2.1.jar:3.2.1]
   at org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry$1.doApply(SimpleFunctionRegistry.java:256) ~[spring-cloud-function-context-3.2.1.jar:3.2.1]
   at org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry$FunctionInvocationWrapper.apply(SimpleFunctionRegistry.java:550) ~[spring-cloud-function-context-3.2.1.jar:3.2.1]
   at org.springframework.cloud.stream.function.FunctionConfiguration$FunctionToDestinationBinder.bindFunctionToDestinations(FunctionConfiguration.java:512) ~[spring-cloud-stream-3.2.1.jar:3.2.1]
   at org.springframework.cloud.stream.function.FunctionConfiguration$FunctionToDestinationBinder.afterPropertiesSet(FunctionConfiguration.java:418) ~[spring-cloud-stream-3.2.1.jar:3.2.1]
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863) ~[spring-beans-5.3.13.jar:5.3.13]
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.3.13.jar:5.3.13]