EventTracker.cs

public class EventTracker<TDelegate>
    where TDelegate : class
{
    public static implicit operator TDelegate( EventTracker<TDelegate> tracker )
    {
        return tracker.Delegate;
    }

    public EventTracker()
    {
        var delegateMeta = typeof( TDelegate ).GetMethod( "Invoke" );
        var delegateParams = delegateMeta
            .GetParameters()
            .Map( param => param.ParameterType )
            .Prepend( GetType() )
            .ToArray<Type>();

        var invokedMethod = GetType().GetMethod( "Invoked", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public );

        var dynamicHandler = new DynamicMethod( "", delegateMeta.ReturnType, delegateParams, GetType(), true );
        var generator = dynamicHandler.GetILGenerator();
        generator.Emit( OpCodes.Ldarg_0 );
        generator.Emit( OpCodes.Call, invokedMethod );
        generator.Emit( OpCodes.Ret );

        Delegate = dynamicHandler.CreateDelegate( typeof( TDelegate ), this ) as TDelegate;
    }

    public TDelegate Delegate
    {
        get;
        private set;
    }

    public int CallCount
    {
        get;
        private set;
    }

    public bool WasCalled
    {
        get { return CallCount > 0; }
    }

    public bool WasNotCalled
    {
        get { return !WasCalled; }
    }

    // called via the dynamic method
    private void Invoked()
    {
        CallCount++;
    }
}