Moq converts It.IsAny<Exception> to It.IsAny<string> in expectation

Question

I'm using Moq for unit tests, and I've set up an expectation like this:

myMock.Expect(w => w.MyMethod(It.IsAny<string>(),
                              It.IsAny<string>(),
                              It.IsAny<string>(),
                              It.IsAny<System.Exception>(), null))
      .Returns(myResult);

the method it is mocking is:

logger.WriteLogItem(string1, string2, string3, System.Exception, 
                    IEnumerableInstantiation);

This builds and runs fine, however VerifyAll() does not pass, and the error I get is:

Moq.MockVerificationException : The following expectations were not met:
IMyClass l => l.MyMethod(It.IsAny<string>(), It.IsAny<string>(), 
                         It.IsAny<string>(), It.IsAny<String>(), null)

So it's changing the Exception to a string for some reason....

Has anyone seen this before/ have any idea why it's doing this and what I can do to fix it/work around it?

thanks!

Answer 1

Okay, so I created a test method that had an exception as a parameter and called that using moq in the way above, and it worked fine. So it doesn't seem to be a problem with passing an Exception as a parameter per se.

I also changed the first parameter from an enum value to an It.IsAny enum. So from

myMock.Expect(w => w.MyMethod(MyEnum.Value,
It.IsAny<string>(),
It.IsAny<string>(),
It.IsAny<System.Exception>(), null))
.Returns(myResult);

to

myMock.Expect(w => w.MyMethod(It.IsAny<MyEnum>(),
It.IsAny<string>(),
It.IsAny<string>(),
It.IsAny<System.Exception>(), null))
.Returns(myResult);

and the output I got was:

IMyClass l => l.MyMethod(IsAny<MyEnum>(), IsAny<MyEnum>(), IsAny<MyEnum>(), IsAny<MyEnum>(), null)

So it looks like it's taking the type of the first parameter and applying it to all the rest for some reason.....

Answer 2

Ah, it was a rookie error! And the conversion thing was just a red-herring designed to send me chasing round the internet looking for crazy answers that aren't out there.

I wasn't passing the myMock.Object through to the calling command!