public async Task CanIncrementCounter() {
var metrics = new InMemoryMetricsClient();
await metrics.CounterAsync("c1");
Assert.Equal(1, metrics.GetCount("c1"));
await metrics.CounterAsync("c1", 5);
Assert.Equal(6, metrics.GetCount("c1"));
var counter = metrics.Counters["c1"];
Assert.True(counter.Rate > 400);
await metrics.GaugeAsync("g1", 2.534);
Assert.Equal(2.534, metrics.GetGaugeValue("g1"));
await metrics.TimerAsync("t1", 50788);
var stats = metrics.GetMetricStats();
Assert.Equal(1, stats.Timings.Count);
metrics.DisplayStats(_writer);
}