JUnit Mock outside rest call via restTemplate

Question

I am trying to write an Integration test where I have an issue in mocking the rest call which is calling outside server using JUnit. I have added a @Mock and @InjectMock on service

Service looks like this.

@Service
public class BoundaryDeltaService {
    private BoundaryDelta getBoundaryDeltaUsingApp() {
       List<BoundaryValueInfo> infoFromSource = Arrays.asList(serviceAdapter.readInfoFromApiUsingApp(boundarySet, app, loginUserInfo));
      return  getBoundaryDeltacompareCurrentBoundaryValuesWithSource(boundarySet, infoFromSource );
    }
}

There is another service with has restTemplate call

@Service
public class ServiceAdapter {
    public BoundaryValueInfo[] readInfoFromApiUsingApp(){
        String loginToken = systemUserLoginService.getSystemUserTokenManual(app, loginUserInfo);
        restTemplate = createRestTemplate(boundarySet);
        HttpHeaders headers = new HttpHeaders() {{
          String authHeader = "Bearer " + loginToken;
          set( "Authorization", authHeader );
        }};

        HttpEntity<String> request = new HttpEntity<String>(headers);
        ResponseEntity<BoundaryValueInfo[]> answerFromApi = restTemplate.exchange(boundarySet.getApiUri(), HttpMethod.GET, request,  BoundaryValueInfo[].class);
        return getResponseFromApi(answerFromApi);
    }
}

And this is the test scenario

@RunWith(SpringJUnit4ClassRunner.class)
@ActiveProfiles({"aws", "local"})
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT, classes = FlywayConfig.class)
@DirtiesContext(classMode = DirtiesContext.ClassMode.BEFORE_CLASS)
public class BoundaryValueDeltaControllerTest {

    private static final String API_V1 = "/api/v1/";

    @Autowired
    TestRestTemplate testRestTemplate;

    @Autowired
    private BoundaryDeltaService boundaryDeltaService;

    @Autowired
    private DomainBuilder domainBuilder;

    @Autowired
    private AppBuilder appBuilder;

    @Autowired
    private AppAdminBuilder appAdminBuilder;

    @Autowired
    private BoundaryValueBuilder boundaryValueBuilder;

    @Autowired
    private BoundarySetBuilder boundarySetBuilder;

    @MockBean
    private LoginUserProvider loginUserProvider;
    @MockBean
    private LoginTokenService loginTokenService;
    @InjectMocks
    private BoundaryServiceAdapter boundaryServiceAdapter;

    @Mock
    RestTemplate restTemplate;

    @LocalServerPort
    private int port;

    Domain domain;
    App app;
    BoundarySet boundarySet;
    BoundaryValue boundaryValue;
    LoginUserInfo loggedInUser;

    @Before
    public void setUp() {
        clear();
        domain = domainBuilder.persist();
        app = appBuilder.persist(domain);
        boundarySet =  boundarySetBuilder.persist(domain);
        boundaryValue = boundaryValueBuilder.persist(boundarySet);
    }

    @After
    public void tearDown() {
        clear();
    }

    @BeforeClass
    public static void setupTestEnv() {
        // https://github.com/localstack/localstack/issues/592
    }

    @Test
    public void updateBoundaryValuesFromApi() {
        aLoggedInUser(domain.getAuthor().getUsername());
        appAdminBuilder.persist(app, domain.getAuthor());
        ResponseEntity<BoundaryValueInfo[]> answerFromApi = getBoundaryValueInfos();

        HttpHeaders headers = new HttpHeaders() {{
            String authHeader = "Bearer 1234";
            set( "Authorization", authHeader );
        }};

        HttpEntity<String> request = new HttpEntity<>(headers);
        //when(restTemplate.exchange(boundarySet.getApiUri(), HttpMethod.GET, request,  BoundaryValueInfo[].class)).thenReturn(answerFromApi);

        when(restTemplate.exchange(ArgumentMatchers.anyString(),
                ArgumentMatchers.any(HttpMethod.class),
                ArgumentMatchers.any(),
                ArgumentMatchers.<Class<BoundaryValueInfo[]>>any())
        ).thenReturn(answerFromApi);

        String url = url(API_V1 + "domains/" + domain.getName() + "/boundarysets/" + boundarySet.getBoundarySetName() + "/app/" + app.getName()+ "/updatefromapi/");
        ResponseEntity<String> response = testRestTemplate.exchange(url,HttpMethod.GET, null, String.class);

        assertEquals(HttpStatus.OK, response.getStatusCode());
    }
}

I am calling controller with api and from there it is going into above services which has rest call but not able to mock the actual call. Can someone guide me here ?

Answer 1

You are not using the TestRestTemplate for the purpose it is intended for.

TestRestTemplate is not an extension of RestTemplate, but rather an alternative that simplifies integration testing and facilitates authentication during tests. It helps in customization of Apache HTTP client, but also it can be used as a wrapper of RestTemplate

Solution:

Approach1: 1) Directly call the exchange method using RestTemplate object.

    ResponseEntity<String> response = restTemplate .exchange(url,HttpMethod.GET, null, String.class);

2) Mock the testRestTemplate and do the mock when on the exchange method call for this object.

    when(testRestTemplate.exchange(ArgumentMatchers.anyString(),
            ArgumentMatchers.any(HttpMethod.class),
            ArgumentMatchers.any(),
            ArgumentMatchers.<Class<BoundaryValueInfo[]>>any())
    ).thenReturn(answerFromApi);