MockitoException-是一个*void方法*并且它*不能*用一个*return value*挂接！

Question

我正在使用Mockito进行单元测试，我得到了以下异常。

org.mockito.exceptions.base.MockitoException: 
`'setResponseTimeStampUtc'` is a *void method* and it *cannot* be stubbed with a *return value*!
Voids are usually stubbed with Throwables:
    doThrow(exception).when(mock).someVoidMethod();
***

If you're unsure why you're getting above error read on.
Due to the nature of the syntax above problem might occur because:
1. The method you are trying to stub is *overloaded*. Make sure you are calling the right overloaded version.
2. Somewhere in your test you are stubbing *final methods*. Sorry, Mockito does not verify/stub final methods.
3. A spy is stubbed using `when(spy.foo()).then()` syntax. It is safer to stub spies - 
   - with `doReturn|Throw()` family of methods. More in javadocs for Mockito.spy() method.

@Repository
public class CardRepositoryImpl implements ICardRepository {        
    @Autowired
    private OperationBean operation;

    @Override
    public OperationBean getCardOperation(final String cardHolderId, final String requestTimeStamp) {
        operation.setRequestTimeStampUtc(requestTimeStamp);
        operation.setResponseTimeStampUtc(DateUtil.getUTCDate());
        return operation;
    }
}

@RunWith(MockitoJUnitRunner.class)
public class CardRepositoryImplUnitTestFixture_Mockito {
    @InjectMocks
    private CardRepositoryImpl cardRepositoryImpl;
    private OperationBean operationBean;

    @Before
    public void beforeTest() {
        MockitoAnnotations.initMocks(this);
    }
    @Test
    public void canGetCardOperation(){
        when(cardRepositoryImpl.getCardOperation("2", Mockito.anyString())).thenReturn(operationBean);

    }    
}

这是否是return语句的一个问题，因为format（）方法是最后一个方法。

public static String getUTCDate() {
    final TimeZone timeZone = TimeZone.getTimeZone("UTC");
    final Calendar calendar = Calendar.getInstance(timeZone);
    final SimpleDateFormat simpleDateFormat = new SimpleDateFormat("YYYY-MM-dd'T'HH:mm:ss.SSS'Z'");
    simpleDateFormat.setTimeZone(timeZone);
    return simpleDateFormat.format(calendar.getTime());
}

我该如何解决这件事？

Answer 1

@InjectMocks
private CardRepositoryImpl cardRepositoryImpl;

when(cardRepositoryImpl.getCardOperation("2", Mockito.anyString()))
    .thenReturn(operationBean);

CardRepositoryImpl不是一个模拟，因此您不能将其存根。通过@injectmocks,您将指示Mockito构造一个真正的CardRepositoryImpl,并将其私有字段和构造函数参数替换为测试用例上的字段。你可能会想用间谍代替；稍后再详细介绍。

但首先，为什么会出现错误消息？因为它不是模拟，所以对CardRepositoryImpl.GetCardOperation的调用发生在实际的CardRepositoryImplhtml" target="_blank">实例上。Mockito看到了与operationbean（看起来确实是一个模拟）的交互，将when和thenreturn视为与最近的模拟调用相对应，并错误地告诉您使用返回值截短了一个void方法（重要的是，错误的方法）。

在对CardRepositoryImpl的测试中，您不应该嘲弄CardRepositoryImpl，也不应该让它返回值：这不会测试任何东西，除了Mockito是否工作。您可能应该重新考虑您需要存根什么，以使您的测试工作。

但是，当截尾一个方法时，您可能希望截尾同一类中的另一个方法。这可以通过间谍来完成：

@Test
public void canGetCardOperation(){
    CardRepositoryImpl spyImpl = spy(cardRepositoryImpl);
    when(spyImpl.getCardOperation(Mockito.eq("2"), Mockito.anyString()))
        .thenReturn(returnValue);
    // ...
    spyImpl.someOtherMethod();  // Any matching calls to getCardOperation from
                                // someOtherMethod will use the stub above.
}

注意：在截短时，您可以相邻地使用anystring和“2”。当使用类似anystring的匹配器时，如果对任何参数使用它们，则需要对所有参数使用它们。看这里更多。