AsyncFactory.cs

public class AsyncFactory {

    public static Task<int> GetIntAsync() {
            
        var tcs = new TaskCompletionSource<int>();

        var timer = new System.Timers.Timer(2000);
        timer.AutoReset = false;
        timer.Elapsed += (s, e) => {
            tcs.SetResult(10);
            timer.Dispose();
        };

        timer.Start();
        return tcs.Task;
    }
}