How to mock the ResponseEntity with generic type?

Question

I need to mock a service. i m getting null in ResponseEntity<?> resp while mocking the class.

Method which need to mock:

public List<Expression> getExpression(String expressView, Localdate date) {

    List<Expression> =new ArrayList<>();
    Map<String, Object> uri = new HashMap<>();
    UriComponenetsBuilder build = 
        UriComponentsBuilder.fromHttpUrl("someUrl" + "/" + expressView);
    build.queryParam(someParameter, someParameter);
    build.queryParam(someParameter, someParameter);
    build.queryParam(someParameter, someParameter);

    HttpHeaders header = new HttpHeaders();
    header.setContentType(MediaType.APPLICATION_JSON);
    RestClient client = new RestClient(
        build.build().encode.toUriString, HttpMethod.GET.Uri, header
    );

    ResponseEntity<?> resp = restC.SomeMethod(client);

    if (resp = !null) {
        //it goes to these line
    }

  }

In my mock method:

when(restC.SomeMethod(client)).thenReturn(resp);

So above method call a service get some data get the value of expressView and save as list. when i mocked the method when(restC.SomeMethod(client)).thenReturn(resp); it hit the URL but the value i m getting as response resp is null . So here i m getting the resp value as null. I checked the URL(someUrl) in postman its returning the value.

How to mock the ResponseEntity<?>?

Thanks.

Possible duplicate of [Junit Mockito test case for ResponseEntity> in spring integration framework](https://stackoverflow.com/questions/39015830/junit-mockito-test-case-for-responseentity-in-spring-integration-framework) — Juliano Macedo, Oct 14 '18 at 14:08
Hi , @J.Macedo i tried this example still getting the null value. — Still Alive, Oct 14 '18 at 14:12

Juliano Macedo · Answer 1 · 2019-09-04T17:51:03.187

First, create a ResponseEntity object:

HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON);

ResponseEntity<?> responseEntity = new ResponseEntity<>(
    "some response body",
    header, 
    HttpStatus.OK
);

Then build a mock to return the responseEntity object:

when(restC.SomeMethod(client)).thenReturn(responseEntity);

Point to pay attention:

Avoid to use ResponseEntity inside @Service class. You should use ResponseEntity in @RestController class.

And you can Inject your @Service class using @Autowired annotation, like:

@RestController
public class YourControllerClass {

    @Autowired
    private YourServiceClass yourServiceClass;

Or using constructor, like:

@RestController
public class YourControllerClass {

    private YourServiceClass yourServiceClass;

    public YourControllerClass(YourServiceClass yourServiceClass) {
        this.yourServiceClass= yourServiceClass;
    }

So:

@Service class will handle business or data objects and @RestController class will handle Response and Request objects. Thus we have Single Responsibility principle.

Some nice links:

Hope this helps!

I improved my answer with suggestions, examples and some nice links ;) I hope this will help you. — Juliano Macedo, Oct 14 '18 at 15:32

How to mock the ResponseEntity with generic type?

1 Answers1