I was sharing what I’d learned about unit testing private methods with some co-workers, and the idea of testing a private method of an abstract class was presented.
PrivateObject deals with this handily by allowing you to specify the type being tested in one of its constructors.
Here’s a simple example. Consider we have an abstract class, Mammal, and a derived class, Human.
public abstract class Mammal
{
private void SecretMammalStuff()
{
}
}
public class Human : Mammal
{
}
We can test Mammal’s private method by doing the following:
var human = new Human();
var po = new PrivateObject(human, new PrivateType(typeof(Mammal)));
po.Invoke("SecretMammalStuff");
If we don’t specify the PrivateType argument in the PrivateObject constructor, we’re not able to access the base class’s private methods. This is the key to testing private methods in an abstract class.
