public void ShouldCallTheCallbackOnlyOnceRegardlessOfAdvanceCalls() { var calls = 0; var tween = new TweenCallback(() => calls++); tween.Advance(new TimeSpan(1)); tween.Advance(new TimeSpan(1)); tween.Advance(new TimeSpan(1)); Assert.Equal(1, calls); Assert.True(tween.IsFinished); }