Mockito avançado: capturadores de argumentos e spies

ArgumentCaptor: capturando argumentos de métodos

Criando e usando ArgumentCaptor

@Test
void sends_correct_email() {
    ArgumentCaptor<EmailMessage> captor = ArgumentCaptor.forClass(EmailMessage.class);
    userService.register(new CreateUserRequest("alice@example.com"));
    verify(emailService).send(captor.capture());
    EmailMessage msg = captor.getValue();
    assertEquals("alice@example.com", msg.getTo());
    assertTrue(msg.getSubject().contains("Welcome"));
}

Anotação @Captor

@ExtendWith(MockitoExtension.class)
class UserServiceTest {
    @Mock EmailService emailService;
    @Captor ArgumentCaptor<EmailMessage> emailCaptor;
    @Test
    void captures_email() {
        // ...
        verify(emailService).send(emailCaptor.capture());
        assertEquals("Welcome!", emailCaptor.getValue().getSubject());
    }
}

Capturando várias chamadas

verify(emailService, times(3)).send(emailCaptor.capture());
List<EmailMessage> messages = emailCaptor.getAllValues();
assertEquals(3, messages.size());
assertEquals("Confirmation", messages.get(0).getSubject());

Spies do Mockito: simulação parcial

List<String> realList = new ArrayList<>();
List<String> spy = Mockito.spy(realList);
spy.add("hello"); // calls real ArrayList.add()
System.out.println(spy.size()); // 1 — real method called
doReturn(42).when(spy).size(); // stub just size()
System.out.println(spy.size()); // 42 — stubbed

Anotação @Spy

@ExtendWith(MockitoExtension.class)
class OrderServiceTest {
    @Spy
    OrderService orderService = new OrderService(mockRepo, mockEmail);
}

Usando spies em beans do Spring com @SpyBean

@SpringBootTest
class IntegrationTest {
    @SpyBean EmailService emailService;
    @Test
    void order_sends_email() {
        orderService.placeOrder(cart);
        verify(emailService).sendConfirmation(any());
    }
}

doReturn versus when().thenReturn() para spies

// Correct for spies:
doReturn(List.of()).when(spy).findAll();
// WRONG for spies — calls real findAll() first:
when(spy.findAll()).thenReturn(List.of()); // real method called!

Verificando a ausência de interações

verifyNoInteractions(emailService); // never called
verify(repo).save(any());
verifyNoMoreInteractions(repo); // save() was the only interaction

Verificação em ordem

InOrder inOrder = inOrder(repo, emailService);
inOrder.verify(repo).save(any());
inOrder.verify(emailService).send(any()); // save happened BEFORE send

Correspondentes de argumentos

verify(repo).save(argThat(user ->
    user.getEmail().endsWith("@example.com") &&
    user.getStatus() == UserStatus.ACTIVE));

Verificação rápida

Recapitulação