How to mock RestTemplate exchange? - spring

Question

I want to unit test assignApplicationsToUser. A list of applicationId and user id is given and I have a URL to validate a user. I am getting an exception mentioned below.
java.lang.NullPointerException: Cannot invoke "com.fasterxml.jackson.databind.JsonNode.asText()" because the return value of "com.fasterxml.jackson.databind.JsonNode.get(String)" is null
AssignmentService.java
public class AssignmentService implements AssignemetServiceInterface {
#Autowired
AppInterceptor appInterceptor;
#Autowired
AssignmentRepository assignmentRepository;
#Autowired
private RestTemplate restTemplate;
private String uri="http://localhost:8080/api/users/"+uuid;
#Override
public List<String> assignApplicationsToUser(List<String> applications, String uuid)
throws SQLException, RequestEntityNotFoundException {
HttpHeaders headers = new HttpHeaders();
headers.set("token", appInterceptor.getLoggedInUser());
HttpEntity<String> requestEntity = new HttpEntity<>(null, headers);
String result = restTemplate.exchange(uri, HttpMethod.GET, requestEntity, String.class).getBody();
ObjectMapper objectMapper = new ObjectMapper();
List<String> response = new ArrayList<>();
JsonNode responseJson = objectMapper.readTree(result);
if (responseJson.get("data") == null
&& responseJson.get("error").get("status").asText().equals("NOT_FOUND")) {
throw new RequestEntityNotFoundException(uuid, "find");
}
for (String application : applications) {
ApplicationAssignment isAssigned = assignmentRepository.findOneByApplicationId(application);
if (isAssigned != null) {
isAssigned.setIsUser(true);
response.add(application + " reassigned to "+ uuid);
isAssigned.setAssignedTo(uuid);
this.assignmentRepository.save(isAssigned);
}
else {
ApplicationAssignment newApplication = new ApplicationAssignment(application, uuid, true);
this.assignmentRepository.save(newApplication);
response.add(application + " assigned successfully");
}
}
return response;
}
}
sample input:
{
applications :["APP001","APP002","APP003","APP004"],
uuid : "user1"
}
Edited :
I have added sample response for the same.
{
"data": {
"id": "fa727274-5a74-428a-b0f6-501eebafd8e8",
"name": "Akash",
"email": "AkashTyagi#fico.com",
"phone": 8799190991,
"isActive": true,
"createdBy": "abhishekjaiswal#fico.com",
"updatedBy": null,
"creationTimeStamp": "2021-08-11T11:23:05.356+00:00",
"updationTimeStamp": null
},
"error": null,
"timeStamp": "2021-08-16T05:02:04.866+00:00",
"success": true
}
AssignmentServiceTest.java
#RunWith(MockitoJUnitRunner.class)
#SpringBootTest
public class AssignmentServiceTest {
private static final Logger LOGGER = LoggerFactory.getLogger(AssignmentServiceTest.class);
#InjectMocks
private AssignmentService assignmentService;
#Mock
private AssignmentRepository assignmentRepo;
#Mock
private AppInterceptor appInterceptor;
#Mock
private RestTemplate restTemplate;
ObjectMapper objectMapper;
String jsonString="{\r\n"
+ " \"data\": {\r\n"
+ " \"id\": \"fa727274-5a74-428a-b0f6-501eebafd8e8\",\r\n"
+ " \"name\": \"Akash\",\r\n"
+ " \"email\": \"AkashTyagi#fico.com\",\r\n"
+ " \"phone\": 8799190991,\r\n"
+ " \"isActive\": true,\r\n"
+ " \"createdBy\": \"abhishekjaiswal#fico.com\",\r\n"
+ " \"updatedBy\": null,\r\n"
+ " \"creationTimeStamp\": \"2021-08-11T11:23:05.356+00:00\",\r\n"
+ " \"updationTimeStamp\": null\r\n"
+ " },\r\n"
+ " \"error\": null,\r\n"
+ " \"timeStamp\": \"2021-08-16T05:02:04.866+00:00\",\r\n"
+ " \"success\": true\r\n"
+ "}";;
JsonNode mock;
#BeforeEach
private void setUp() throws JsonMappingException, JsonProcessingException {
objectMapper = new ObjectMapper();
mock = org.mockito.Mockito.mock(JsonNode.class);
}
#Test
public void test_assignApplicationsToUser() throws NullPointerException, SQLException, RequestEntityNotFoundException, IndexOutOfBoundsException,JsonProcessingException, URISyntaxException{
LOGGER.info("Begin of test_assignApplicationToUser method");
ApplicationAssignment applicationAssignment = new ApplicationAssignment("1","u1",true);
ApplicationAssignment savedApplicationAssignment = new ApplicationAssignment("1","u2",true);
ResponseEntity<String> myEntity = new ResponseEntity<String>("{\r\"error\":null\r}",HttpStatus.ACCEPTED);
Mockito.when(restTemplate.exchange(
ArgumentMatchers.anyString(),
ArgumentMatchers.any(HttpMethod.class),
ArgumentMatchers.any(),
ArgumentMatchers.<Class<String>>any())).thenReturn(myEntity);
Mockito.when(appInterceptor.getLoggedInUser()).thenReturn("abhishek#fico.com");
Mockito.when(mock.get("data")).thenReturn(mock);
Mockito.when(mock.get("error")).thenReturn(mock);
Mockito.when(mock.get("error").asText()).thenReturn("FOUND");
LOGGER.info("Node value "+ mock.asText());
Mockito.when(assignmentRepo.findOneByApplicationId("1")).thenReturn(applicationAssignment);
Mockito.when(assignmentRepo.save(ArgumentMatchers.any())).thenReturn(savedApplicationAssignment);
// Mock the input List of applications
List<String> listOfApplication = new ArrayList<>();
listOfApplication.add("app1");
listOfApplication.add("app2");
List<String> response = assignmentService.assignApplicationsToUser(listOfApplication,"u1");
assertEquals(response.get(0),"app1 assigned successfully");
}
}

Answer 1

In main code, create two pojos as below which would represent response of the rest call.
#JsonIgnoreProperties(ignoreUnknown = true)
public class UserDataResponse {
#JsonProperty("data")
UserInfo userInfo;
#JsonProperty("error")
String error;
#JsonProperty("success")
boolean success;
}
#JsonIgnoreProperties(ignoreUnknown = true)
public class UserInfo {
#JsonProperty("id")
String id;
#JsonProperty("name")
String name;
#JsonProperty("email")
String email;
#JsonProperty("phone")
String phone;
#JsonProperty("isActive")
boolean isActive;
#JsonProperty("createdBy")
String createdBy;
#JsonProperty("updatedBy")
String updatedBy;
}
In AssignmentService class change your code to get the response as below since this is better way to handle the rest response based on the HttpStatus code rather than trying to element in the json. So your main rest call would look like as below:
String result = restTemplate.exchange(uri, HttpMethod.GET, requestEntity, String.class);
if(result.getStatusCode()==HttpStatus.OK){
UserDataResponse userDataResponse = readResponse(result,UserDataResponse.class);
}else if(result.getStatusCode()==HttpStatus.NOT_FOUND){
throw new RequestEntityNotFoundException(uuid, "find");
}
// You can make below code as part of the helper class and use it anywhere you want.
private <T> T readResponse(ResponseEntity<String> responseEntity,Class<T> classType){
T object;
try {
object = objectMapper.readValue(responseEntity.getBody(),classType);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
return null;
}
Testing Code:
Mock all the variables of service like AppInterceptor, repository and resttemplate to be injectto AssignmentService.
Put all the below code in test class like AssingmentServiceTest
#Mock
AppInterceptor appInterceptor;
#Mock
AssignmentRepository assignmentRepository;
#Mock
RestTemplate restTemplate;
#InjectMocks
AssignmentService assignmentService;
ObjectMapper objectMapper = new ObjectMapper();
#Test
public void test_assignApplicationsToUser(){
UserDataResponse restResponse = new UserDataResponse();
String jsonString="{\r\n"
+ " \"data\": {\r\n"
+ " \"id\": \"fa727274-5a74-428a-b0f6-501eebafd8e8\",\r\n"
+ " \"name\": \"Akash\",\r\n"
+ " \"email\": \"AkashTyagi#fico.com\",\r\n"
+ " \"phone\": 8799190991,\r\n"
+ " \"isActive\": true,\r\n"
+ " \"createdBy\": \"abhishekjaiswal#fico.com\",\r\n"
+ " \"updatedBy\": null,\r\n"
+ " \"creationTimeStamp\": \"2021-08-11T11:23:05.356+00:00\",\r\n"
+ " \"updationTimeStamp\": null\r\n"
+ " },\r\n"
+ " \"error\": null,\r\n"
+ " \"timeStamp\": \"2021-08-16T05:02:04.866+00:00\",\r\n"
+ " \"success\": true\r\n"
+ "}";
restResponse = readResponse(jsonString, UserDataResponse.class);
ResponseEntity<String> myEntity = new ResponseEntity<String>(restResponse.toString(),HttpStatus.OK);
Mockito.when(resttemplate.exchange(
ArgumentMatchers.anyString(),
ArgumentMatchers.any(HttpMethod.class),
ArgumentMatchers.any(),
ArgumentMatchers.<Class<String>>any())
).thenReturn(myEntity);
// You can create a ApplicationAssignment pojo and pass it in thenReturn
ApplicationAssignment applicationAssignment = new ApplicationAssingment(1,"sd");
Mockito.when(assignmentRepository.findOneByApplicationId(ArgumentMatchers.any())).thenReturn(assignmentRepository);
Mockito.when(appInterceptor.getLoggedInUser).thenReturn("token");
// You can mock the response here but looks like that response is not used anywhere
ApplicationAssignment savedApplicationAssignment = new ApplicationAssignment(1,"ss");
Mockito.when(assignmentRepository.save(ArgumentMatchers.any())).thenReturn(savedApplicationAssignment);
// Mock the input List of applications
List<String> listOfApplication = new ArrayList<>();
listOfApplication.add("app1");
listOfApplication.add("app2");
List<String> response = assignmentService.assignApplicationsToUser(listOfApplication,"1212");
assertEquals(response[0],"app1 reassigned to 1212");
}