public void TestAverage()
{
var clock = new MemoryClock();
var activityTracker = new ActivityTracker <MyCounters>(clock, TimeSpan.FromSeconds(10));
var collection = new CounterCollection <MyCounters>();
// Initial rates are (total: 0, ratePerSecond: 0)
Dictionary <MyCounters, (long total, double ratePerSecond)> rates = activityTracker.GetRates();
rates[MyCounters.Value1].Should().Be((0, 0));
rates[MyCounters.Value2].Should().Be((0, 0));
clock.AddSeconds(1);
collection.AddToCounter(MyCounters.Value1, 1);
collection.AddToCounter(MyCounters.Value2, 2);
activityTracker.ProcessSnapshot(collection);
rates = activityTracker.GetRates();
// Totals should be changed, but the rates are still 0. We don't have enough data.
rates[MyCounters.Value1].Should().Be((1, 0));
rates[MyCounters.Value2].Should().Be((2, 0));
clock.AddSeconds(1);
collection.AddToCounter(MyCounters.Value1, 1);
collection.AddToCounter(MyCounters.Value2, 2);
activityTracker.ProcessSnapshot(collection);
rates = activityTracker.GetRates();
rates[MyCounters.Value1].Should().Be((2, 1));
rates[MyCounters.Value2].Should().Be((4, 2));
// Moving the time to the end of the window
clock.AddSeconds(9);
collection.AddToCounter(MyCounters.Value1, 2);
collection.AddToCounter(MyCounters.Value2, 4);
activityTracker.ProcessSnapshot(collection);
rates = activityTracker.GetRates();
rates[MyCounters.Value1].Should().Be((4, 0.3));
rates[MyCounters.Value2].Should().Be((8, 0.6));
// Move even further, should have only one record in the window.
clock.AddSeconds(3);
rates = activityTracker.GetRates();
rates[MyCounters.Value1].Should().Be((4, 0));
rates[MyCounters.Value2].Should().Be((8, 0));
clock.AddSeconds(2); // 5 seconds since the last snapshot
collection.AddToCounter(MyCounters.Value1, 5);
collection.AddToCounter(MyCounters.Value2, 10);
activityTracker.ProcessSnapshot(collection);
rates = activityTracker.GetRates();
rates[MyCounters.Value1].Should().Be((9, 1));
rates[MyCounters.Value2].Should().Be((18, 2));
}