Moq:如何获取传递给模拟服务方法的参数

Question

想象一下这堂课

public class Foo {

    private Handler _h;

    public Foo(Handler h)
    {
        _h = h;
    }

    public void Bar(int i)
    {
        _h.AsyncHandle(CalcOn(i));
    }

    private SomeResponse CalcOn(int i)
    {
        ...;
    }
}

Mo(q)cking Handler在Foo的测试中,我怎样才能检查Bar()传递给了_h.AsyncHandle什么？

Answer 1

您可以使用Mock.Callback方法:

var mock = new Mock<Handler>();
SomeResponse result = null;
mock.Setup(h => h.AnsyncHandle(It.IsAny<SomeResponse>()))
    .Callback<SomeResponse>(r => result = r);

// do your test
new Foo(mock.Object).Bar(22);
Assert.NotNull(result);

如果您只想在传入的参数中检查一些简单的东西,您也可以直接执行:

mock.Setup(h => h.AnsyncHandle(It.Is<SomeResponse>(response => response != null)));

Answer 2

另一种方法是使用Capture.In，这是 Moq 中的开箱即用功能，可让您将参数捕获到集合中：

//Arrange
var args = new List<SomeResponse>();
mock.Setup(h => h.AsyncHandle(Capture.In(args)));

//Act
new Foo(mock.Object).Bar(22);

//Assert
//... assert args.Single() or args.First()

Answer 3

Gamlor的回答是有效的,但另一种做法(以及我认为在测试中更具表现力的一种方式)是......

var mock = new Mock<Handler>();
var desiredParam = 47; // this is what you want to be passed to AsyncHandle
new Foo(mock.Object).Bar(22);
mock.Verify(h => h.AsyncHandle(desiredParam), Times.Once());

验证非常强大,值得花时间习惯.

Answer 4

Gamlor的回答对我有用,但我想我会扩展John Carpenter的评论,因为我正在寻找一个涉及多个参数的解决方案.我认为偶然发现此页面的其他人可能处于类似情况.我在Moq文档中找到了这个信息.

我将使用Gamlor的示例,但让我们假装AsyncHandle方法有两个参数:a string和一个SomeResponse对象.

var mock = new Mock<Handler>();
string stringResult = string.Empty;
SomeResponse someResponse = null;
mock.Setup(h => h.AsyncHandle(It.IsAny<string>(), It.IsAny<SomeResponse>()))
    .Callback<string, SomeResponse>((s, r) => 
    {
        stringResult = s;
        someResponse = r;
    });

// do your test
new Foo(mock.Object).Bar(22);
Assert.AreEqual("expected string", stringResult);
Assert.IsNotNull(someResponse);

基本上,您只需要It.IsAny<>()使用适当的类型添加另一个类型,向该Callback方法添加另一个类型,并根据需要更改lambda表达式.

Answer 5

Callback方法肯定会起作用,但如果你在一个有很多参数的方法上这样做,它可能有点冗长.这是我用来删除一些样板的东西.

var mock = new Mock<Handler>();

// do your test   
new Foo(mock.Object).Bar(22);

var arg = new ArgumentCaptor<SomeResponse>();
mock.Verify(h => h.AsyncHandle(arg.Capture()));
Assert.NotNull(arg.Value);

以下是ArgumentCaptor的来源:

public class ArgumentCaptor<T>
{
    public T Capture()
    {
        return It.Is<T>(t => SaveValue(t));
    }

    private bool SaveValue(T t)
    {
        Value = t;
        return true;
    }

    public T Value { get; private set; }
}

Answer 6

这也有效：

Mock<InterfaceThing> mockedObject = new Mock<InterfaceThing>();
var objectParameter = mockedObject.Invocations[1].Arguments[0] as ObjectParameter;

Answer 7

您可以使用It.Is<TValue>()匹配器。

var mock = new Mock<Handler>();
new Foo(mock.Object).Bar(22);
mock.Verify(h => h.AsyncHandle(It.Is<SomeResponse>(r => r != null )));