Correct way to unit test the type of an object

drl picture drl · Mar 12, 2014 · Viewed 30.1k times · Source

Using the Visual Studio Unit Testing Framework, I'm looking at two options:

Assert.AreEqual(myObject.GetType(), typeof(MyObject));

and

Assert.IsInstanceOfType(myObject, typeof(MyObject));

Is there a difference between these two options? Is one more "correct" than the other?

What is the standard way of doing this?

Answer

Lee picture Lee · Mar 12, 2014

The first example will fail if the types are not exactly the same while the second will only fail if myObject is not assignable to the given type e.g.

public class MySubObject : MyObject { ... }
var obj = new MySubObject();

Assert.AreEqual(obj.GetType(), typeof(MyObject));   //fails
Assert.IsInstanceOfType(obj, typeof(MyObject));     //passes