I\'m new to unit testing and NUit in particular. I\'m just typing some examples from the book which refers to Java and JUnit. But I\'m using C# instead.
The problem
I suspect your problem is that you haven't overridden overload the equality == operator. Under the hood the Assert.AreEqual is probably using ==.
See Operator Overloading Tutorial.
Update: I ran the NUnit test through the debugger and it does indeed use the Equals method and not the == operator.