using System;

using System.Threading;

using System.Threading.Tasks;

​

public class Program

{

    public static void Main()

    {

        var test = new Test();

        Console.WriteLine(test.TestAsync(true).Result);

        Console.WriteLine(Await(async t => await t.TestAsync(false)).Result);

    }

​

    public static Task<bool> Await(Func<Test, Task<bool>> function)

    {

        var test = new Test();

        return function(test);

    }

​

    public class Test

    {

        public Task<bool> TestAsync(bool initial)

        {

            var tcs = new TaskCompletionSource<bool>();

            var client = new AsyncTest();

            EventHandler<bool> handler = null;

            handler = (sender, result) =>

            {

                client.Completed -= handler;

                if (result == initial)

                {

                    tcs.SetException(new Exception("This should have flipped"));

                }

                else

                {

                    tcs.TrySetResult(result);

                }

            }

​

            ;

            client.Completed += handler;

            client.TestAsync(initial);

            return tcs.Task;

        }

    }

​

    public class AsyncTest

    {

        public event EventHandler<bool> Completed;

        public void TestAsync(bool initial)

        {

            Thread.Sleep(50);

            var temp = Completed;

            if (temp != null)

            {

                temp(this, !initial);

            }

        }

    }

}