为什么使用 It.is <>或 It.IsAny<>如果我可以定义一个变量? [英] Why use It.is<> or It.IsAny<> if I could just define a variable?

问题描述

当我看到这段代码时，我已经使用 moq 一段时间了.

Hi I've been using moq for a while when I see this code.

我必须在我的一个仓库中设置退货.

I have to setup a return in one of my repo.

 mockIRole.Setup(r => r.GetSomething(It.IsAny<Guid>(), It.IsAny<Guid>(), 
                  It.IsAny<Guid>())).Returns(ReturnSomething);

我有三个参数，我只是在网上的一篇文章或博客中看到这些参数.

I have three parameters and I just saw these in one of articles or blog on the net.

It.Is<> 或 It.IsAny<> 对对象有什么用?如果我可以使用 Guid.NewGuid() 或其他类型，那为什么要使用 It.Is?

What is the use of It.Is<> or It.IsAny<> for an object? if I could use Guid.NewGuid() or other types then why use It.Is?

很抱歉，我不确定我的问题是否正确，或者我在测试中遗漏了一些知识.不过好像也没什么问题.

I'm sorry I'm not sure if my question is right or am I missing some knowledge in testing. But it seems like there is nothing wrong either way.

推荐答案

使用 It.IsAny<>、It.Is<> 或变量 all服务于不同的目的.在设置或验证方法时，它们提供了越来越具体的方法来匹配参数.

Using It.IsAny<>, It.Is<>, or a variable all serve different purposes. They provide increasingly specific ways to match a parameter when setting up or verifying a method.

使用It.IsAny<> 设置的方法将匹配您提供给该方法的任何 参数.因此，在您的示例中，以下调用都将返回相同的内容 (ReturnSomething):

The method set up with It.IsAny<> will match any parameter you give to the method. So, in your example, the following invocations would all return the same thing (ReturnSomething):

role.GetSomething(Guid.NewGuid(), Guid.NewGuid(), Guid.NewGuid());

Guid sameGuid = Guid.NewGuid();
role.GetSomething(sameGuid, sameGuid, sameGuid);

role.GetSomething(Guid.Empty, Guid.NewGuid(), sameGuid);

传递的 Guid 的实际值无关紧要.

It doesn't matter the actual value of the Guid that was passed.

It.Is<> 构造对于方法的设置或验证很有用，让您可以指定与参数匹配的函数.例如:

The It.Is<> construct is useful for setup or verification of a method, letting you specify a function that will match the argument. For instance:

Guid expectedGuid = ...
mockIRole.Setup(r => r.GetSomething(
                 It.Is<Guid>(g => g.ToString().StartsWith("4")), 
                 It.Is<Guid>(g => g != Guid.Empty), 
                 It.Is<Guid>(g => g == expectedGuid)))
         .Returns(ReturnSomething);

这使您可以限制值而不仅仅是任何值，但允许您对接受的内容保持宽容.

This allows you to restrict the value more than just any value, but permits you to be lenient in what you accept.

当您使用变量设置(或验证)方法参数时，您是在说您需要正是该值.使用另一个值调用的方法永远不会匹配您的设置/验证.

When you set up (or verify) a method parameter with a variable, you're saying you want exactly that value. A method called with another value will never match your setup/verify.

Guid expectedGuids = new [] { Guid.NewGuid(), Guid.NewGuid(), Guid.NewGuid() };
mockIRole.Setup(r => r.GetSomething(expectedGuids[0], expectedGuids[1], expectedGuids[2]))
         .Returns(ReturnSomething);

现在只有一种情况 GetSomething 将返回 ReturnSomething:当所有 Guid 与您设置的预期值匹配时.

Now there's exactly one case where GetSomething will return ReturnSomething: when all Guids match the expected values that you set it up with.

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