Question

I’m trying to add a unit test to an authentication class I have. So, basically what it does is I call Login and I expect that it will return true and as a side effect will add a cookie.

Here is my unit test so far:

var mock=new Mock<IServerContext>(); //AddCookie method is within IServerContext
FSCAuth.Config.Server=mock; //set authentication to use mocked interface
mock.Setup(x=>x.AddCookie(new HttpCookie().Name=="??")); //question here
FSCAuth.Login("foo", "bar", false);
mock.VerifyAll();

My question is how can I check the argument passed into AddCookie? Basically, all I want to do is something like

bool AddCookieVerify(HttpCookie cookie)
{
    return cookie.Name=="foobar"
}

and if my verify function returns false, then throw an error. I don’t understand how to express this operation though in Moq.

How do I do this?

Answer 1

Moq includes the It static class to let you specify what types of arguments you’re expecting. For instance, instead of your placeholder line

mock.Setup(x => x.AddCookie(new HttpCookie().Name == "??"));

you can do

mock.Setup(x => x.AddCookie(It.Is<HttpCookie>(cookie => cookie.Name == "Whatever")));

And then it will fail verification unless it’s passed a value that satisfies that expression.

Also, you might think about switching from Setup() followed by VerifyAll() to something that simply uses Verify() after the fact, such as:

var mock = new Mock<IServerContext>(); // AddCookie method is within IServerContext
FSCAuth.Config.Server = mock.Object; //set authentication to use mocked interface
FSCAuth.Login("foo", "bar", false);
mock.Verify(x => x.AddCookie(It.Is<HttpCookie>(cookie => cookie.Name == "Whatever")), Times.Once());

This avoids the need for you to explicitly set up your expectations in advance, and gets it down to one extra line of code.