public void TearDown()
 {
     _taskScheduler.Dispose();
     PendingTask.GetActivePeriodicTimersCount().Should().Be(0);
     PendingTask.GetActivePeriodicSlTimersCount().Should().Be(0);
     PendingTask.GetExecutingActionsCount().Should().Be(0);
     PendingTask.GetActiveTimersCount().Should().Be(0);
 }