Is it possible to pass-through parameter values in Moq?

Question

I need to mock HttpResponseBase.ApplyAppPathModifier in such a way that the parameter ApplyAppPathModifier is called with is automatically returned by the mock.

I have the following code:

var httpResponseBase = new Mock<HttpResponseBase>();
httpResponseBase.Setup(hrb => hrb.ApplyAppPathModifier(/*capture this param*/))
                .Returns(/*return it here*/);

Any ideas?

EDIT:

Found a solution on the first page of Moq documentation (http://code.google.com/p/moq/wiki/QuickStart):

var httpResponseBase = new Mock<HttpResponseBase>();
httpResponseBase.Setup(hrb => hrb.ApplyAppPathModifier(It.IsAny<string>)
                .Returns((string value) => value);

I suddenly feel a lot stupider, but I guess this is what happens when you write code at 23:30

Answer 1

Yes, you can echo back the argument passed to the method

httpResponseBase.Setup(x => x.ApplyAppPathModifier(It.IsAny<string>()))
                .Returns((string path) => path);

You can also capture it if you want

string capturedModifier = null;

httpResponseBase.Setup(x => x.ApplyAppPathModifier(It.IsAny<string>()))
                .Callback((string path) => capturedModifier = path);

Answer 2

Use It:

It.Is<MyClass>(mc=>mc == myValue)

Here you can check the expectation: the value you expect to receive. In terms of return, just return value you need.

var tempS = string.Empty;
var httpResponseBase = new Mock<HttpResponseBase>();
httpResponseBase.Setup(hrb => hrb.ApplyAppPathModifier(It.Is<String>(s=>{
           tempS = s;
           return s == "value I expect";
           })))
                .Returns(tempS);