/// <summary>
 /// 使用state的值恢复Current的值
 /// </summary>
 /// <param name="state"></param>
 public static void RestoreCurrentState(TimePointContext state)
 {
     if (state != null)
     {
         TimePointContext.Current._UseCurrentTime = state._UseCurrentTime;
         TimePointContext.Current._SimulatedTime  = state._SimulatedTime;
     }
 }
        /// <summary>
        /// 得到当前TimePointContext的值
        /// </summary>
        /// <returns></returns>
        public static TimePointContext GetCurrentState()
        {
            TimePointContext result = new TimePointContext();

            result._UseCurrentTime = TimePointContext.Current._UseCurrentTime;
            result._SimulatedTime  = TimePointContext.Current._SimulatedTime;

            return(result);
        }