Mockito:doThrow()和thenThrow()之间的区别 [英] Mockito: Difference between doThrow() and thenThrow()

问题描述

doThrow()和thenThrow()有什么区别?

比方说，我们要模拟身份验证服务以验证用户的登录凭据.如果我们要模拟一个异常，那么以下两行有什么区别?

Let's say, we want to mock an authentication service to validate the login credentials of a user. What's the difference between the following two lines if we were to mock an exception?

doThrow(new BadCredentialsException("Wrong username/password!")).when(authenticationService).login("user1", "pass1");

vs

when(authenticationService.login("user1", "pass1")).thenThrow(new BadCredentialsException("Wrong username/password!"));

推荐答案

几乎没有:在简单情况下，它们的行为完全相同. when语法读起来更像是英语中的语法句子.

Almost nothing: in simple cases they behave exactly the same. The when syntax reads more like a grammatical sentence in English.

为什么差不多"?请注意，when样式实际上包含对authenticationService.login的调用.那是该行中评估的第一个表达式，因此，在调用when的过程中，无论发生任何行为，都会发生.大多数时候，这里没有问题:方法调用没有存根行为，因此Mockito仅返回一个虚拟值，并且这两个调用完全相同.但是，如果满足以下任一条件，则可能不是这种情况:

Why "almost"? Note that the when style actually contains a call to authenticationService.login. That's the first expression evaluated in that line, so whatever behavior you have stubbed will happen during the call to when. Most of the time, there's no problem here: the method call has no stubbed behavior, so Mockito only returns a dummy value and the two calls are exactly equivalent. However, this might not be the case if either of the following are true:

• 您正在改写已经打断的行为，特别是运行答案"或引发异常
• 您正在与间谍一起实施非平凡的实现

在这种情况下，doThrow将调用when(authenticationService)并停用所有危险行为，而when().thenThrow()将调用危险方法并退出测试.

In those cases, doThrow will call when(authenticationService) and deactivate all dangerous behavior, whereas when().thenThrow() will invoke the dangerous method and throw off your test.

(当然，对于void方法，您还需要使用doThrow-when语法只有在没有返回值的情况下才能编译.那里没有选择.)

(Of course, for void methods, you'll also need to use doThrow—the when syntax won't compile without a return value. There's no choice there.)

因此，doThrow通常总是更安全一些，但是when().thenThrow()更具可读性，并且通常等效.

Thus, doThrow is always a little safer as a rule, but when().thenThrow() is slightly more readable and usually equivalent.

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