mod vhost_tests {
    use super::*;
    #[test]
    fn exclusive_bins_reconstruct_exact_prometheus_cumulative_boundaries() {
        let m = VhostMetrics::default();
        m.active.store(5, Ordering::Relaxed);
        for micros in [1, 5_000, 5_001, 25_000, 5_000_001] {
            m.complete(200, false, std::time::Duration::from_micros(micros), 0, 1040);
        }
        let (cumulative, total) = m.duration_histogram();
        assert_eq!(total, 5);
        assert_eq!(cumulative, [2, 3, 4, 4, 4, 4, 4, 4, 4, 4]);
        assert_eq!(n(&m.buckets[0]), 2);
        assert_eq!(n(&m.buckets[1]), 1);
        assert_eq!(n(&m.buckets[2]), 1);
        assert_eq!(n(&m.buckets[10]), 1);
        assert_eq!(n(&m.completed), 5);
        assert_eq!(n(&m.active), 0);
    }

    #[test]
    fn streaming_completion_and_histogram() {
        let m = VhostMetrics::default();
        m.active.store(1, Ordering::Relaxed);
        m.complete(503, false, std::time::Duration::from_millis(20), 10, 50);
        assert_eq!(n(&m.active), 0);
        assert_eq!(n(&m.errors), 1);
        assert_eq!(n(&m.status[4]), 1);
        assert_eq!(n(&m.buckets[1]), 0);
        assert_eq!(n(&m.buckets[2]), 1);
        assert_eq!(n(&m.buckets[10]), 0); // exclusive +Inf bin
        let (buckets, count) = m.duration_histogram();
        assert_eq!(buckets[1], 0);
        assert_eq!(buckets[2], 1);
        assert_eq!(buckets[9], 1);
        assert_eq!(count, 1);
        let view = m.view();
        assert_eq!(view.requests, 0);
        assert_eq!(view.completed, 1);
        assert_eq!(view.errors, 1);
        assert!(view.ewma_latency_ms >= 20.0);
    }
}

mod compression_counter_tests {
    use super::*;
    use crate::compression::AppliedEncoding;

    #[test]
    fn each_codec_has_an_independent_counter() {
        let metrics = Metrics::default();
        for encoding in [
            AppliedEncoding::Gzip,
            AppliedEncoding::Brotli,
            AppliedEncoding::Zstd,
            AppliedEncoding::Deflate,
        ] {
            metrics.record_compression(encoding);
        }
        let view = metrics.view();
        assert_eq!(view.compression_gzip, 1);
        assert_eq!(view.compression_br, 1);
        assert_eq!(view.compression_zstd, 1);
        assert_eq!(view.compression_deflate, 1);
    }
}