使用NUnit 2.6，是否可以具有两个对象，例如Assert.AreEqual和Assert.AreNotSame都为TRUE？

Question

To all:

I am trying to write a short C# application in which I'm trying to run two NUnit Assert statements for which I want BOTH to be true:

Assert.AreEqual(object1, object1);
Assert.AreNotSame(object1, object2);

It seems possible but I have not had luck making this particular circumstance happen. I want to instantiate two objects (object1, object2 above) that should evaluate true when using .Equals() but should evaluate false if using the " == " operator.

Can NUnit do this?

Thanks!

Answer 1

A conditional yes to the first question and title. No to the last the one about == operator!

This works

var object1 = new MyObject(someparameter);
var object2 = new MyObject(someotherparameter);

Assert.AreNotSame(object1, object2);
Assert.AreEqual(object1, object2); // See following

But only if you have overridden the Equals() method of the object in a way that it evaluates as true. It's up to you to define equality for your own objects.

On the other hand, this fails

var object1 = new object();
var object2 = new object();

Assert.AreNotSame(object1, object2);
Assert.AreEqual(object1, object2); // Fails!

The failure is because object equality is defined in .NET as being the same object. The two only behave differently for classes where equality has been defined in a different way. That's true whether the Type is a .NET Type or one of your own.

The == operator on object gives object equality (same object). It too only works differently for Types on which it has been defined differently. For your own Types, you would have to define it yourself if you want it to work.

By the way, your question really has nothing to do with NUnit per se. NUnit mostly tries to mimic what the .NET framework does for equality, although it adds a few "extras" like allowing ints to be equal to doubles when using an assert.