spring-mvc: how to test Rx responses with mockMvc?

Question

my controller is:

import rx.Single;
...

@GetMapping
Single<List<MyType>> fetchFromDB() {
        return Single
                .fromCallable(() -> dao.fetch())
                .subscribeOn(Schedulers.io());
}

and it works perfectly. but i can't tests it. i tried:

 MvcResult asyncResult = mvc.perform(get("/")).andReturn()

 String result = mvc
                    .perform(asyncDispatch(asyncResult))
                    .andReturn().getResponse().getContentAsString()

but it fails with:

java.lang.IllegalStateException: Async result for handler [rx.Single<java.util.List<MyType>> MyController.fetchFromDB()] was not set during the specified timeToWait=-1

    at org.springframework.test.web.servlet.DefaultMvcResult.getAsyncResult(DefaultMvcResult.java:145)
    at org.springframework.test.web.servlet.DefaultMvcResult.getAsyncResult(DefaultMvcResult.java:121)
    at org.springframework.test.web.servlet.request.MockMvcRequestBuilders.asyncDispatch(MockMvcRequestBuilders.java:246)
    at MyControllerSpec.should fetch from db...

so: how to test rx.Single with spring mvc?

Please check answer provided [here](https://stackoverflow.com/a/45033122/1290868) — myuce, Jul 11 '17 at 11:22

score 3 · Accepted Answer · answered Oct 24 '16 at 15:42

3

i found the answer. when you create your mockMvc object, add a handler for Single:

return MockMvcBuilders.standaloneSetup(controller)
                .setCustomReturnValueHandlers(new SingleReturnValueHandler())

answered Oct 24 '16 at 15:42

piotrek

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score 1 · Answer 2 · answered Aug 03 '17 at 15:00

if you use MockMvcBuilders.webAppContextSetup(context) instead, you can add the handler in your WebMvcConfigurerAdapter:

public class Config extends WebMvcConfigurerAdapter {

    @Override
    public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
        returnValueHandlers.add(new SingleReturnValueHandler());
    }
}

spring-mvc: how to test Rx responses with mockMvc?

2 Answers2