We Keep Coding

Right way of testing method that depends on other method calls

Hi have read a lot about this but can't come to a conclusion about the best way to test a method that is dependent on other method call results to perform its actions.
Some of the questions I've read include:
Testing methods that depend on each other
Unit testing a method that calls other methods
Unit testing a method that calls another method
Some of the answers sugest that we should only test the methods that perform only one action and then test the method that call this methods for conditional behaviuour (for example, verifying if a given method was called or not) and that's fine, I get it, but I'm struggling with other scenario.
I have a service with a REST api.
The controller has a create method that receives a DTO and calls the Service class create method with this argument (DTO).
I'm trying to practice TDD and for this I use this project I'm building without a database.
The code is as follows:
#Service
public class EntityService implements FilteringInterface {
private MemoryDatabase db = MemoryDatabase.getInstance();
//Create method called from controller: receives DTO to create a new
//Entity after validating that it's name and code parameters are unique
public EntityDTO create(EntityDTO dto) throws Exception {
validateUniqueFields(dto);
Entity entity = Entity.toEntity(dto, "id1"); //maps DTO to Entity object
db.add(entity);
return new EntityDTO.Builder(entity);//maps entity to DTO
}
public void validateUniqueFields(EntityDTO dto) throws Exception {
Set<Entity> foundEntities = filterEntityByNameOrCode(dto.getName(),
dto.getCode(), db.getEntities());
if (!foundEntities.isEmpty()) {
throw new Exception("Already exists");
}
}
}
This is the interface with methods reused by other service classes:
public interface FilteringInterface {
default Set<Entity> filterEntityByNameOrCode(String name, String code, Set<Entity> list) {
return list.stream().filter(e -> e.getSiteId().equals(siteId)
&& (e.getName().equals(name)
|| e.getCode().equals(code))).collect(Collectors.toSet());
}
default Optional<Entity> filterEntityById(String id, Set<Entity> list) {
return list.stream().filter(e -> e.getId().equals(id)).findAny();
};
}
So, I'm testing this service class and I need to test the create() method because it can have different behaviors:
If the received DTO has a name that already exists on the list of entities -> throws Exception
If the received DTO has a code that already exists on the list of entities -> throws Exception
If the received DTO has a name and a code that already exists on the list of entities -> throws Exception
If name and code are different, than everything is ok, and creates the entity -> adds the entity to the existing list - > converts the entity to DTO and retrieves it.
Problem:
To test any of the scenarios, suppose, scenario 1: I need to make the filterEntityByNameOrCode() method return a list with an Entity that has the same name as the Entity I'm trying to create. This method is called inside validateUniqueFields() method.
Problem is: I can't call mockito when() for any of this methods because, for that, I would have to mock the service class, which is the class that I'm testing and, thus, it's wrong approach.
I've also read that using Spy for this is also wrong approach.
So, where thus that leaves me?
Also: if this code is not the correct aprocah, and thats why
it can't be correctly tested, than, whats should the correct approach be?
This service will have other methods (delete, update, etc.). All of this methods will make use of the FilteringInterface as well, so I will have the same problems.
What is the correct way of testing a service class?

I would apply an DI pattern in your service, in order to mock and control the db variable.
#Service
public class EntityService implements FilteringInterface {
private Persistence db;
public EntityService(Persistence db) {
this.db = db;
}
}
After that, you will be able to add entities to Set accordingly to your scenarios
#ExtendWith(MockitoExtension.class)
class EntityServiceTest {
#Mock
private Persistence persistence;
#InjectMocks
private EntityService entityService;
#BeforeEach
void before() {
final Set<Entity> existentEntity = Set.of(new Entity(1L,1L, "name", "code"));
when(persistence.getEntities()).thenReturn(existentEntity);
}
#Test
void shouldThrowWhenNameAlreadyExists() {
final EntityDTO dto = new EntityDTO(1L, "name", "anything");
assertThrows(RuntimeException.class, () -> entityService.create(dto));
}
#Test
void shouldThrowWhenCodeAlreadyExists() {
final EntityDTO dto = new EntityDTO(1L, "anything", "code");
assertThrows(RuntimeException.class, () -> entityService.create(dto));
}
#Test
void shouldThrowWhenNameAndCodeAlreadyExists() {
final EntityDTO dto = new EntityDTO(1L, "name", "code");
assertThrows(RuntimeException.class, () -> entityService.create(dto));
}
#Test
void shouldNotThrowWhenUnique() {
final EntityDTO dto = new EntityDTO(1L, "diff", "diff");
final EntityDTO entityDTO = entityService.create(dto);
assertNotNull(entityDTO);
}
}

Mockito failing inside internal call for mocked method

I'm trying to mock the return value for a method using the when call from mockito. However, I'm new to this and I may perhaps be misunderstanding how mockito works, since the call is failing inside the method mocked when that calls another method. I thought regardless of how that method is implemented, I should be getting the return value I'm asking for? Or do I need to mock also the internals for that method? I feel that shouldn't be it.
public boolean verifyState(HttpServletRequest request, String s) {
String stateToken = getCookieByName(request, STATE_TOKEN);
String authToken = getCookieByName(request, AUTHN);
boolean isValidState = true;
if (isValidState) {
try {
log.info(getEdUserId(stateToken, authToken));
return true;
} catch (Exception e) {
ExceptionLogger.logDetailedError("CookieSessionUtils.verifyState", e);
return false;
}
} else {
return false;
}
}
public String getEdUserId(String stateToken, String authToken) throws Exception {
String edUserId;
Map<String, Object> jwtClaims;
jwtClaims = StateUtils.checkJWT(stateToken, this.stateSharedSecret); // Failing here not generating a proper jwt token
log.info("State Claims: " + jwtClaims);
edUserId = sifAuthorizationService.getEdUserIdFromAuthJWT(authToken);
return edUserId;
}
My test:
#ActiveProfiles(resolver = MyActiveProfileResolver.class)
#WebMvcTest(value = CookieSessionUtils.class, includeFilters = {
#ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = {ApiOriginFilter.class, ValidationFilter.class})})
class CookieSessionUtilsTest {
#Autowired
private CookieSessionUtils cookieSessionUtils; // Service class
#Mock
private CookieSessionUtils cookieSessionUtilsMocked; // Both the method under test and the one mocked are under the same class, so trying these two annotations together.
#Mock
private HttpServletRequest request;
#BeforeEach
public void setUp() {
MockitoAnnotations.initMocks(this);
}
#Test
public void testVerifyState1() throws Exception {
//...Some mocks for getCookieName
UUID uuid = UUID.randomUUID();
when(cookieSessionUtils.getEdUserId(anyString(), anyString()).thenReturn(eq(String.valueOf(uuid))); // When this line runs it fails on verifyState method
assertTrue(cookieSessionUtils.verifyState(request, ""));
}
UPDATE
Attempt using anyString() instead of eq().
Thank you.

Your test is broken in a few places.
Setting expectations on a real object
You should call Mockito.when on mocks and spies, not on System under test. Mockito normally reports it with a clear error message, but you throw a NPE from getEdUserId, so this is reported instead. The NPE stems from the fact that both eq and anyString return null, which is passed to the real method.
Invalid use of matchers
As #StefanD explained in his answer eq("anyString()") is not matching any string. It matches only one string "anyString()"
Returning a mather instead of real object
thenReturn(eq(String.valueOf(uuid)))
This is illegal position for a matcher.
Mixing Mockito and Spring annotations in a WebMvcTest
This is a common error. Mockito does not inject beans to the spring context.
From the code provided it is unclear what CookieSessionUtils is (Controller? ControllerAdvice?) and what is the correct way to test it.
Update
It seems that you are trying to replace some methods under test. A way to do it is to use a Spy.
See https://towardsdatascience.com/mocking-a-method-in-the-same-test-class-using-mockito-b8f997916109
The test written in this style:
#ExtendWith(MockitoExtension.class)
class CookieSessionUtilsTest {
#Mock
private HttpServletRequest request;
#Mock
private SifAuthorizationService sifAuthorizationService;
#Spy
#InjectMocks
private CookieSessionUtils cookieSessionUtils;
#Test
public void testVerifyState1() throws Exception {
Cookie cookie1 = new Cookie("stateToken", "stateToken");
Cookie cookie2 = new Cookie("Authn", "Authn");
when(request.getCookies()).thenReturn(new Cookie[]{cookie1, cookie2});
UUID uuid = UUID.randomUUID();
doReturn(String.valueOf(uuid)).when(cookieSessionUtils).getEdUserId(anyString(), anyString());
assertTrue(cookieSessionUtils.verifyState(request, ""));
}
}
An alternative way is to call the real method, but to mock all collaborators: StateUtils and sifAuthorizationService. I would probably go with this one, if you want to test public getEdUserId.
Test written when mocking collaborators:
#ExtendWith(MockitoExtension.class)
class CookieSessionUtilsTest {
#Mock
private HttpServletRequest request;
#Mock
private SifAuthorizationService sifAuthorizationService;
#InjectMocks
private CookieSessionUtils cookieSessionUtils;
#Test
public void testVerifyState1() throws Exception {
Cookie cookie1 = new Cookie("stateToken", "stateToken");
Cookie cookie2 = new Cookie("Authn", "Authn");
when(request.getCookies()).thenReturn(new Cookie[]{cookie1, cookie2});
UUID uuid = UUID.randomUUID();
when(sifAuthorizationService.getEdUserIdFromAuthJWT(cookie2.getValue())).thenReturn(String.valueOf(uuid));
assertTrue(cookieSessionUtils.verifyState(request, ""));
}
}
I took the assumption that StateUtils.checkJWT does not need to be mocked
The points above are still valid and need to be resolved in either case.
Remarks
As the system under test is currently a Service, I suggest to drop WebMvcTest and test it with plain mockito instead.
Should SUT be a service? It is more typical to handle auth code in filters.
note usage of doReturn when stubbing a method on a spy.
You use mocks in more places than needed. For example Cookie is trivial to construct, there is no point in using a mock

The error is here:
when(cookieSessionUtils.getEdUserId(eq("anyString()"), eq("anyString()"))).thenReturn(eq(String.valueOf(uuid)));
It should read like
when(cookieSessionUtils.getEdUserId(anyString()), anyString()).thenReturn(uuid);
Please refer to the Mockito documentation of Argument matchers.
Because the argument matchers looking for the string "anyString()" they never match the actual parameters the method call is providing and so there is never returned the uuid you expecting.

WrongTypeOfReturnValue: "Object" cannot be returned by findById()

I am trying to do tests for my Spring boot application, and I've got a big problem. This is how my error looks like:
org.mockito.exceptions.misusing.WrongTypeOfReturnValue:
WorkItem cannot be returned by findById()
findById() should return Optional
I was following tutorials and everyone is using findOne(), but for me it just doesn't work. My IDE shows:
" Inferred type 'S' for type parameter 'S' is not within its bound; should extend 'com.java.workitemservice.model.WorkItem"
That's why I tried it the other way and used findById(), but then I got another error.
{
#RunWith(SpringRunner.class)
#SpringBootTest
public class WorkitemServiceApplicationTests {
#Mock
private WorkItemRepository workItemRepository;
#InjectMocks
WorkItemsController workItemsController;
#Before
public void init() {
MockitoAnnotations.initMocks(this);
}
#Test
public void testGetUserById() {
WorkItem workItem = new WorkItem();
workItem.setId(1L);
//old version
//when(workItemRepository.findOne(1L)).thenReturn(workItem);
when(workItemRepository.findById(1L).orElse(null)).thenReturn(workItem);
WorkItem workItem2 = workItemsController.getWorkItemById(1L);
verify(workItemRepository).findById(1L).orElse(null);
assertEquals(1L, workItem2.getId().longValue());
}
}
My Repository :
#Repository
public interface WorkItemRepository extends JpaRepository<WorkItem,
Long> {
Optional <WorkItem> findWorkItemBySubject(String subject);
}
My service method:
public WorkItem getWorkItemById(Long id) {
return this.workItemRepository.findById(id)
.orElseThrow(() -> new
ResourceNotFoundException("WorkItem", "id", id));
}
My Controller method :
#GetMapping("/workItems/{id}")
public WorkItem getWorkItemById(#PathVariable(value = "id") Long
workItemId) {
return this.workItemService.getWorkItemById(workItemId);
}
}

As the error states, you are not returning what the method signature declares as a return type (which is Optional<WorkItem>)
Just return
Optional.of(workitem)
instead of workItem, i.e :
when(workItemRepository.findById(1L).orElse(null)).thenReturn(Optional.of(workitem));

I see in comments that you tried this :
when(workItemRepository.findById(1L).orElse(null)).thenReturn(Optional.of(workitem));
It should be working.
I think the problem is comming from your 'orElse' call.
To be precise, here is the method when :
public static <T> OngoingStubbing<T> when(T methodCall) {
return MOCKITO_CORE.when(methodCall);
}
So i think that using 'orElse' prevent 'T' from being inferred.
And my question is why using 'orElse' ?
You're stubbing the method.
You can use 'anyString' to match any parameter.
Cheers

Try this:
when(workItemRepository.findById(1L)).thenReturn(Optional.of(Optional.of(workitem).get()));
It woked for me

Mockito Error : However, there was exactly 1 interaction with this mock

Hello i try to use mockito, to verify user password if invalid i want to verify it show error message.
But i got this following error :
Wanted but not invoked:
loginView.showPasswordError();
-> at android.fanjavaid.com.tdd_android_login.LoginActivityTest.invalidPassword_notLoggedIn_showPasswordError(LoginActivityTest.java:84)
However, there was exactly 1 interaction with this mock:
loginView.showEmailError();
-> at android.fanjavaid.com.tdd_android_login.presenter.LoginPresenterImpl.validateInput(LoginPresenterImpl.java:23)
Here is my test method :
#Test
public void invalidEmail_notLoggedIn_showEmailError() {
LoginPresenter presenter = new LoginPresenterImpl(loginView, validator);
presenter.validateInput(user);
verify(loginView).showEmailError();
}
#Test
public void invalidPassword_notLoggedIn_showPasswordError() {
when(user.getEmailAddress()).thenReturn("fanjavaid#gmail.com");
LoginPresenter presenter = new LoginPresenterImpl(loginView, validator);
presenter.validateInput(user);
verify(loginView).showPasswordError();
}
I already mock the email user in invalidPassword_notLoggedIn_showPasswordError() with valid input, but i still get that error message.
Here is my Presenter implementation :
#Override
public void validateInput(User user) {
if (!validator.validateEmail(user.getEmailAddress())) {
view.showEmailError();
} else if (validator.validatePassword(user.getPassword())) {
view.showPasswordError();
}
}
What i am missing for?
Thank you

✔ ANSWER
After several minutes explore again, i found something interesting.
I forgot to add mock to one class.
Below i mock some classes moreless like this :
#RunWith(MockitoJUnitRunner.class)
public class LoginActivityTest {
#Mock User user;
#Mock LoginView loginView;
#Mock MyValidator validator;
LoginPresenter presenter;
#Before
public void beforeTest() {
presenter = new LoginPresenterImpl(loginView, validator);
}
...
You can see that i mock validator class.
I got the error because in invalidPassword_notLoggedIn_showPasswordError() method i didn't add mock value for email validation.
// Mock validation
when(validator.validateEmail(user.getEmailAddress())).thenReturn(true);
If i don't mock it, it will ask about showEmailError() but we just verify showPasswordError()
This cause my implementation using condition to check one by one, started from check email is valid or not, then password valid or not.
If email doesn't exists and return value from validator doesn't exists the error will occured.
So i need to mock email address as valid and mock validator to return true(valid email).
That's my explanation and hope can help anyone who try mockito.

Decoupling a Mockito test from a specifc test value?

I am trying to test the method findById() method in the class below that reads data from my Database using the CrudRepository:
Class under test:
public interface PersonRepository extends CrudRepository<Person, Integer>
{
Person findById(String id);
}
Below is my test class, the test is currently passing but I would like to change it so that if the id "1" I am testing with is removed from my database, I can still run my test. I.e. do not rely on data within the database.
How can I do so?
Test Class:
public class PersonRepositoryTest {
#Mock
private PersonRepository personRepository;
#Before
public void setUp() throws Exception {
//Initialize the mocked class and ensure that it is not null
MockitoAnnotations.initMocks(this);
assertThat(personRepository, notNullValue());
}
#Test
public void testFindById() throws ParseException {
//test string
String id = "1";
//when it is called, return
when(personRepository.findById(anyString())).thenReturn(new Person());
Person person = personRepository.findById(id);
assertThat(person, notNullValue());
}
}

As mentioned in the Post comments by #Thomas, you are just mocking the database. I'm assuming you want to write a negative test case when the ID is 1.
You can just return null, instead of person Object. Instead of Matchers, pass a specific value to differentiate your positive and negative test cases.
Positive Case -
when(personRepository.findById(2)).thenReturn(new Person());
Negative Case -
when(personRepository.findById(1)).thenReturn(null);