Program.cs

using System;
using System.Threading;
using System.Threading.Tasks;

namespace RunAsync
{
    class Program
    {
        static void Main(string[] args)
        {
            for (var i = 0; i < 1000; i++)
            {
                TestRunAsync(i).Wait();
            }

            Console.WriteLine("Done!");
        }

        static async Task TestRunAsync(int testRun)
        {
            var tcs = new TaskCompletionSource<object>(TaskContinuationOptions.RunContinuationsAsynchronously);
            var mre = new ManualResetEventSlim();

            var tcsAwaiterTask = Task.Run(async () =>
            {
                await tcs.Task;
                if (!mre.Wait(TimeSpan.FromSeconds(10)))
                {
                    Console.WriteLine("Tcs continuation ran inline in test run {0}. Stack trace: {1}", testRun, Environment.StackTrace);
                    throw new Exception();
                }
            });

            var tcsSetterTask = Task.Run(() =>
            {
                tcs.SetResult(null);
                mre.Set();
            });

            await tcsAwaiterTask;
            await tcsSetterTask;
        }
    }
}