using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        TestImplementation testClass = new TestImplementation();

        ITest testInterface = new TestImplementation();

​

        Console.WriteLine("Output when using Implementation is : " + testClass.GetBool() + " .... which makes sense as implementation overrides the default to true");

        Console.WriteLine("Output when using Interface is : " + testInterface.GetBool() +  " .... :huh expected to be true because Implementation overrides the default doesn't it? It's False beacuse the Interface's default is used");

    }

}

​

public interface ITest{

    bool GetBool(bool bla = false); 

}

​

public class TestImplementation : ITest

{

    public bool GetBool(bool inputBool = true)

    {

        return inputBool;

    }

}