Returning value that was passed into a method

Question

I have a method on an interface:

string DoSomething(string whatever);

I want to mock this with MOQ, so that it returns whatever was passed

Answer 1

The generic Returns method can handle this situation nicely.

_mock.Setup(x => x.DoSomething(It.IsAny())).Returns(x => x);

Or if the method requires multiple inputs, specify them like so:

_mock.Setup(x => x.DoSomething(It.IsAny(), It.IsAny())).Returns((string x, int y) => x);