tests: rework the actually useful tests to live in the integration crate

crates/irtt-stats/tests/ipdv.rs

@@ -0,0 +1,112 @@
+use std::time::{Duration, Instant, UNIX_EPOCH};
+
+use irtt_client::{
+    ClientEvent, ClientTimestamp, PacketMeta, RttSample, ServerTiming, SignedDuration,
+};
+use irtt_stats::{StatsCollector, StatsConfig};
+
+fn reply(
+    base: Instant,
+    seq: u32,
+    send_ms: u64,
+    receive_ms: u64,
+    timing: ServerTiming,
+) -> ClientEvent {
+    let raw = Duration::from_millis(receive_ms - send_ms);
+    ClientEvent::EchoReply {
+        seq,
+        remote: "127.0.0.1:2112".parse().unwrap(),
+        sent_at: ClientTimestamp {
+            mono: base + Duration::from_millis(send_ms),
+            wall: UNIX_EPOCH + Duration::from_millis(200 + u64::from(seq) * 10),
+        },
+        received_at: ClientTimestamp {
+            mono: base + Duration::from_millis(receive_ms),
+            wall: UNIX_EPOCH + Duration::from_millis(240 + u64::from(seq) * 20),
+        },
+        rtt: RttSample {
+            raw,
+            adjusted: None,
+            effective: SignedDuration::from_duration(raw),
+        },
+        server_timing: Some(timing),
+        one_way: None,
+        received_stats: None,
+        bytes: 64,
+        packet_meta: PacketMeta::default(),
+    }
+}
+
+#[test]
+fn directional_ipdv_uses_matching_clock_domains_and_preserves_zero_and_absence() {
+    let first = ServerTiming {
+        receive_mono_ns: Some(100_000_000),
+        send_mono_ns: Some(101_000_000),
+        receive_wall_ns: Some(1_000_000_000),
+        send_wall_ns: Some(1_001_000_000),
+        midpoint_mono_ns: None,
+        midpoint_wall_ns: None,
+        processing: None,
+    };
+    let second = ServerTiming {
+        receive_mono_ns: Some(105_000_000),
+        send_mono_ns: Some(108_000_000),
+        receive_wall_ns: Some(1_020_000_000),
+        send_wall_ns: Some(1_026_000_000),
+        ..first
+    };
+    // Wall and monotonic deltas deliberately disagree: availability alone
+    // cannot prove the formulas or which clock domain wins.
+    let mut wall_only = second;
+    wall_only.receive_mono_ns = None;
+    wall_only.send_mono_ns = None;
+    let mut no_send = wall_only;
+    no_send.receive_wall_ns = None;
+    let mut no_receive = wall_only;
+    no_receive.send_wall_ns = None;
+    let zero = ServerTiming {
+        receive_mono_ns: Some(110_000_000),
+        send_mono_ns: Some(111_000_000),
+        ..second
+    };
+    for (label, current, send_ms, expected_send_ms, expected_receive_ms) in [
+        ("monotonic preferred", second, 30, Some(5), Some(3)),
+        ("wall fallback", wall_only, 30, Some(10), Some(5)),
+        ("missing send endpoint", no_send, 30, None, Some(5)),
+        ("missing receive endpoint", no_receive, 30, Some(10), None),
+        ("reordered client send times", second, 10, Some(15), Some(3)),
+        ("zero variation", zero, 30, Some(0), Some(0)),
+    ] {
+        let base = Instant::now();
+        let mut collector = StatsCollector::new(StatsConfig::finite());
+        assert!(collector
+            .process(&reply(base, 0, 20, 40, first))
+            .ipdv_pairs
+            .is_empty());
+        let update = collector.process(&reply(base, 1, send_ms, 50, current));
+        assert_eq!(update.ipdv_pairs.len(), 1, "{label}");
+        let pair = &update.ipdv_pairs[0];
+        assert_eq!(
+            pair.send_ipdv,
+            expected_send_ms.map(Duration::from_millis),
+            "{label}"
+        );
+        assert_eq!(
+            pair.receive_ipdv,
+            expected_receive_ms.map(Duration::from_millis),
+            "{label}"
+        );
+        let snapshot = collector.snapshot();
+        for (expected, actual) in [
+            (expected_send_ms, snapshot.ipdv.send),
+            (expected_receive_ms, snapshot.ipdv.receive),
+        ] {
+            assert_eq!(actual.count, u64::from(expected.is_some()), "{label}");
+            assert_eq!(
+                actual.total_ns,
+                i128::from(expected.unwrap_or(0)) * 1_000_000,
+                "{label}"
+            );
+        }
+    }
+}