public void WhileTyping_SendsTypingEvery4SecondsUntilTaskCompletes()
{
var taskSource = new TaskCompletionSource <int>();
var channelId = "C123";
var result = _sut.WhileTyping(channelId, () => taskSource.Task);
_scheduler.AdvanceBy(TimeSpan.FromSeconds(4).Ticks - 1);
_rtm.DidNotReceive().SendTyping(channelId);
_scheduler.AdvanceBy(1);
_rtm.Received(1).SendTyping(channelId);
_scheduler.AdvanceBy(TimeSpan.FromSeconds(8).Ticks);
_rtm.Received(3).SendTyping(channelId);
taskSource.SetResult(0);
result.IsCompleted.ShouldBe(true);
_scheduler.AdvanceBy(TimeSpan.FromSeconds(4).Ticks);
_rtm.Received(3).SendTyping(channelId);
}