Debug.Listeners
// compile with: csc /r:system.dll file_1.cs using System; using System.Diagnostics; class MyClass { public MyClass(int i) { this.i = i; } [Conditional("DEBUG")] public void VerifyState() { Debug.Assert(i == 0, "Bad State"); } int i = 0; } public class DefensiveProgrammingAsserts { public static void Main() { Debug.Listeners.Clear(); Debug.Listeners.Add(new TextWriterTraceListener(Console.Out)); MyClass c = new MyClass(1); c.VerifyState(); } }