Unit testing for Server.MapPath

Question

I\'ve a method. which retrieve a document from hard disk. I can\'t test this from unit testing. It always throw an exception invalid null path or something. How to test that

Answer 1

I was using NSubstitute and I implemented it as below:

 var fakeContext = Substitute.For();
fakeContext.Server.MapPath(Arg.Any()).ReturnsForAnyArgs("/set-path/");