How to get the value of a mock service with Mockito and Spring

Question

How can I capture the value of an operation on a mock repository, as apposed to overriding the return value.

Take for example this test

@Mock
AccountRepository accountRepository;

@InjectMocks
AccountService accountService;

@Test
public void remove_staff_updates_roles() {

    Account account = new Account("username", "pass");

    when(accountRepository.findByUsername(any(String.class))).thenReturn(Optional.of(account));

    accountService.updateStaffStatusByUsername("user", false);

    // How can I capture the account that is to be saved here?

    assertFalse(????.getValue().getRoles().contains(Role.ROLE_STAFF));
    }

Then in the service

public Account updateStaffStatusByUsername(String username, Boolean toState) {
    Account account;

    if (toState) {
        return addRole(username, Role.ROLE_STAFF);
    }
    return removeRole(username, Role.ROLE_STAFF);
    
}

Account addRole(String username, Role role) {
    Optional<Account> optionalAccount = accountRepository.findByUsername(username);

    if (account.isEmpty()) {
        throw new CustomException("No account exists with the username: " + username, HttpStatus.NOT_FOUND);
    }

    Account account = optionalAccount.get();
    account.addRole(role);

    // I want to intercept this and take the value to evaluate
    return accountRepository.save(account);
}

I want to verify that the state of the account has changed correctly when the service is to save the updated account.

Answer 1

在这里，您正在传递Account （可选）类对象account以响应模拟服务，并且正在更新相同的对象并将其保存在数据库中，因此您需要验证该对象中的值。

 assertFalse(account.getRoles().contains(Role.ROLE_STAFF)); //or vice-verse

Answer 2

It seems to me that ArgumentCaptor is what you need. Try the following:

@Mock
AccountRepository accountRepository;

@InjectMocks
AccountService accountService;

@Test
public void remove_staff_updates_roles() {

    Account account = new Account("username", "pass");

    when(accountRepository.findByUsername(any(String.class))).thenReturn(Optional.of(account));

    accountService.updateStaffStatusByUsername("user", false);

    ArgumentCaptor<Account> accountCaptor = ArgumentCaptor.forClass(Account.class);
    verify(accountRepository).save(accountCaptor.capture());
    assertFalse(accountCaptor.getValue().getRoles().contains(Role.ROLE_STAFF));
}