How to return ResponseEntity when mocking RestTemplate

Question

following is my method which I am trying to unit test

public class Emp {
  public String getName() {
    ResponseEntity<LinkedHashMap> res = restTemplate.postForEntity(url, null, LinkedHashMap.class);
    return res.getBody().get("name");
  }
}

My unit test code is as follows

        LinkedHashMap<String, String> map = new LinkedHashMap<>();
        map.put("name", "foo");
        ResponseEntity<LinkedHashMap> entity = new ResponseEntity<>(map, HttpStatus.OK);

        Mockito.when(restTemplate.postForEntity(Mockito.any(), Mockito.any(), Mockito.any())).thenReturn(entity);

But I am getting compilation error as

java: no suitable method found for thenReturn(org.springframework.http.ResponseEntity<java.util.LinkedHashMap>)

Couldn't get rid of the error after many trial n error.
Can someone point at whats wrong here and how I can fix the unit test code?

thanks

Answer 1

Couldn't get rid of the error after many trial n error. Can someone point at whats wrong here and how I can fix the unit test code?

You have this compilation error because you try to use thenReturn with a generic type ResponseEntity<LinkedHashMap>. Mockito expects you to use thenReturn with a specific instance, but not just a generic type.

You can fix this error by using the ResponseEntity class with the specific generic type which matches your method's return value type:

.
..
...

LinkedHashMap<String, String> map = new LinkedHashMap<>();
map.put("name", "foo");
ResponseEntity<LinkedHashMap<String, String>> entity = new ResponseEntity<>(map, HttpStatus.OK);

Mockito.when(restTemplate.postForEntity(Mockito.anyString(), Mockito.isNull(), Mockito.eq(LinkedHashMap.class)))
               .thenReturn(entity);

...
..
.