C#

if (AssertionCondition == false)
{
Debugger.Break();// :)
//Debug.Assert(false, "Something went wrong");
}

"In the confrontation between the stream and the rock, the stream always wins - not through strength but perseverance." (H. Jackson Brown)

using System;
using System.Diagnostics;

namespace WeeTester
{

	class Class1
	{
		private static int _i = 0;

		[STAThread]
		static void Main(string[] args)
		{
			Console.WriteLine("_i={0}", Add());
			Debug.Assert(Add()==1, "_i != 1");
			Console.WriteLine("_i={0}", Add());

			Console.ReadLine();
		}
		
		private static int Add()
		{
			return _i++;
		}
	}
}

_i=0
_i=2

_i=0
_i=1

"In the confrontation between the stream and the rock, the stream always wins - not through strength but perseverance." (H. Jackson Brown)

WindowsPrincipal myPrincipal;
myPrincipal = (WindowsPrincipal)   System.Threading.Thread.CurrentPrincipal;
WindowsIdentity myIdentity;
myIdentity = (WindowsIdentity)myPrincipal.Identity;
MessageBox.Show(myIdentity.Name);

AppDomain.CurrentDomain.SetPrincipalPolicy   (PrincipalPolicy.WindowsPrincipal);

class C : A     // inherit from A
{
  private B b;  // contain B and add wrapper methods
 
  public void SomeMethodInB()
  {
    b.SomeMethod();
  }
 
  public int SomeOtherMethodInB()
  {
    return b.SomeOtherMethod();
  }
 
  ...
}