how to mock restTemplate getForObject

问题:

I want to test the restTemplate.getForObject method using a mock but having issues. I'm new with Mockito, so I read some blogs about testing restTemplate using Mockito but still can not write a successful test. The class to test is :

package rest;

@PropertySource("classpath:application.properties")
@Service
public class RestClient {

    private String user;
    // from application properties
    private String password;
    private RestTemplate restTemplate;

    public Client getClient(final short cd) {

        restTemplate.getInterceptors().add(new BasicAuthenticationInterceptor(user, password));

        Client client = null;

        try {
            client = restTemplate.getForObject("http://localhost:8080/clients/findClient?cd={cd}",
                    Client.class, cd);
        } catch (RestClientException e) {

            println(e);
        }

        return client;
    }

    public RestTemplate getRestTemplate() {
        return restTemplate;
    }

    public void setRestTemplate(final RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    }
}

My test class :

package test;
@PropertySource("classpath:application.properties")
@RunWith(MockitoJUnitRunner.class)
public class BatchRestClientTest {


    @Mock
    private RestTemplate restTemplate;

    @InjectMocks
    private RestClient restClient;

    private MockRestServiceServer mockServer;

    @Before
    public void setUp() throws Exception {
    }

    @After
    public void tearDown() throws Exception {
    }

    @Test
    public void getCraProcessTest() {
        Client client=new Client();
        client.setId((long) 1);
        client.setCd((short) 2);
        client.setName("aaa");

        Mockito
            .when(restTemplate.getForObject("http://localhost:8080/clients/findClient?cd={cd},
                    Client.class, 2))
            .thenReturn(client);

        Client client2= restClient.getClient((short)2);
        assertEquals(client, client2);
    }

    public RestTemplate getRestTemplate() {
        return restTemplate;
    }

    public void setRestTemplate(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    }

    public RestClient getRestClient() {
        return restClient;
    }

    public void setRestClient(RestClient restClient) {
        this.restClient = restClient;
    }
}

It is returning null and not the expected client, the restTemplate for Object class works fine. I want just to write the test . Am I missing something or doing the test wrong way? Thanks for any guidance.

回答1:

Use this instead:

Mockito.when(restTemplate.getForObject(
    "http://localhost:8080/clients/findClient?cd={id}",
    Client.class,
    new Object[] {(short)2})
).thenReturn(client);

The third parameter is a varargs. So you need to wrap into an Object[] in the test, otherwise Mockito is not able to match it. Note that this happens automatically in your implementation.

Also:

• You forgot to terminate your url (missing closing ") in your examples in the question.
  Probably just a typo.

• You used different url's in your implementation in your test: ...?cd={cd} instead of ...?cd={id}.
  (As previously pointed out by @ArnaudClaudel in the comments).

• You did not define a behaviour for restTemplate.getInterceptors()
  so I would expect it to fail with a NullPointerException,
  when trying to add the BasicAuthenticationInterceptor.

---

Additionally you might want to check my answer here for another example of how to mock the getForObject method. Note that it does not include a case where any of the real parameters would be null.