public void CleanupTest()
{
var time = T(TimeSpan.Zero);
var target = new EventCounter(() => time, TimeSpan.FromMinutes(1));
target.Count("a");
target.Count("a");
target.Count("a");
time = T(TimeSpan.FromMinutes(5));
target.GetSnapshot()
.Should().Contain(i => i.Key == "a");
target.Cleanup();
target.GetSnapshot()
.Should().NotContain(i => i.Key == "a");
}
