Consider the following C# program:

using System;
using System.Diagnostics;

namespace Test
{
        class MainClass
    {
        public static void Main (string[] args)
        {
            Debug.Assert(false);
            Debug.Fail("fail!");
            Console.WriteLine ("Hello World!");
        }
    }
}

When compiling this using:

dmcs -debug -d:DEBUG Main.cs

and then running it with:

mono --debug Main.exe

the assertion and fail seem to be ignored. The output is just:

Hello World!

I checked other related questions on StackOverflow, but I could not find a solution. In particular the solution give in Mono - Debug.Assert does not work does not work. (UPDATE: the update solution does work, see below comments.)

I use Mono 2.1.5-1 on Ubuntu 11.10.