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

crates/irtt-stats/src/ipdv.rs

@@ -185,65 +185,13 @@ mod tests {
         }
     }
 
-    #[test]
-    fn ipdv_tracker_late_wrapped_previous_completes_pair() {
-        let mut tracker = IpdvTracker::new(None);
-        assert!(tracker.insert(ipdv_sample(0, 14)).is_empty());
-
-        let pairs = tracker.insert(ipdv_sample(u32::MAX, 10));
-
-        assert_eq!(
-            pairs,
-            vec![CompletedIpdvPair {
-                previous_seq: u32::MAX,
-                current_seq: 0,
-                rtt_ipdv_ns: 4,
-                send_ipdv_ns: None,
-                receive_ipdv_ns: None,
-            }]
-        );
-    }
-
-    #[test]
-    fn ipdv_tracker_bounded_mode_limits_sequence_state() {
-        let limit = 4;
-        let mut tracker = IpdvTracker::new(Some(limit));
-
-        // Far more inserts than the limit, so eviction runs repeatedly. Every
-        // per-sequence collection must stay bounded by the limit rather than
-        // growing with the number of samples seen, and eviction must not stop
-        // adjacent sequences from still completing a pair.
-        for seq in 0..512_u32 {
-            let pairs = tracker.insert(ipdv_sample(seq, i128::from(seq)));
-
-            assert_eq!(pairs.len(), usize::from(seq > 0), "seq {seq}");
-            assert!(tracker.samples.len() <= limit, "seq {seq}");
-            assert_eq!(
-                tracker.sample_order.len(),
-                tracker.samples.len(),
-                "seq {seq}"
-            );
-            assert!(tracker.completed_pairs.len() <= limit, "seq {seq}");
-        }
-    }
-
     mod properties {
         use super::*;
         use proptest::prelude::*;
 
         proptest! {
-            /// The hand-written `ipdv_tracker_bounded_mode_limits_sequence_state`
-            /// test above only exercises a strictly increasing `0..512`
-            /// sequence. Real traffic can duplicate, skip, or otherwise not
-            /// strictly increase sequence numbers (see the client's
-            /// `LateReply`/`DuplicateReply` handling), so this generates
-            /// arbitrary, possibly-repeated, possibly-non-monotonic sequence
-            /// streams and checks the same bounds still hold after every
-            /// insert: `samples` and `sample_order` never exceed the
-            /// configured limit and stay in lockstep, and `completed_pairs`
-            /// never exceeds `samples.len()` (a successful entry can only
-            /// persist once both its endpoint samples are present, see
-            /// `try_pair`, so it is always a subset of the live sample keys).
+            // Hidden retention state must stay bounded even with duplicates,
+            // gaps and reordered replies; snapshots cannot expose a leak here.
             #[test]
             fn bounded_tracker_state_never_exceeds_the_limit(
                 limit in 1usize..8,
@@ -251,34 +199,26 @@ mod tests {
             ) {
                 let mut tracker = IpdvTracker::new(Some(limit));
                 for seq in seqs {
-                    tracker.insert(ipdv_sample(seq, i128::from(seq)));
+                    let completed_before = tracker.completed_pairs.clone();
+                    let pairs = tracker.insert(ipdv_sample(seq, i128::from(seq)));
+                    let emitted: HashSet<_> = pairs.iter().map(|pair| pair.current_seq).collect();
+                    prop_assert_eq!(emitted.len(), pairs.len());
+                    prop_assert!(emitted.is_disjoint(&completed_before), "a retained pair must not be emitted twice");
                     prop_assert!(tracker.samples.len() <= limit);
+                    prop_assert!(tracker.sample_order.len() <= limit);
+                    prop_assert!(tracker.completed_pairs.len() <= limit);
+                    // Eviction must remove stale pair markers as well as samples;
+                    // otherwise retained state can prevent future adjacent pairs.
                     prop_assert_eq!(tracker.sample_order.len(), tracker.samples.len());
-                    prop_assert!(tracker.completed_pairs.len() <= tracker.samples.len());
+                    prop_assert_eq!(tracker.sample_order.iter().collect::<HashSet<_>>().len(), tracker.samples.len());
+                    prop_assert!(tracker.sample_order.iter().all(|seq| tracker.samples.contains_key(seq)));
+                    prop_assert!(tracker.completed_pairs.iter().all(|seq| {
+                        tracker.samples.contains_key(seq)
+                            && tracker.samples.contains_key(&seq.wrapping_sub(1))
+                    }), "completed pairs must retain both sequence endpoints");
                 }
             }
 
-            /// A pair for a given adjacent `(seq - 1, seq)` boundary is only
-            /// ever emitted once, however many times `insert` is called
-            /// (including for already-seen or unrelated sequences in
-            /// between). This is the unbounded case, so eviction cannot be
-            /// the reason a pair fails to repeat.
-            #[test]
-            fn each_adjacent_pair_is_emitted_at_most_once(
-                seqs in prop::collection::vec(0u32..12, 0..200),
-            ) {
-                let mut tracker = IpdvTracker::new(None);
-                let mut seen_pairs = std::collections::HashSet::new();
-                for seq in seqs {
-                    for pair in tracker.insert(ipdv_sample(seq, i128::from(seq))) {
-                        let key = (pair.previous_seq, pair.current_seq);
-                        prop_assert!(
-                            seen_pairs.insert(key),
-                            "pair {key:?} emitted more than once"
-                        );
-                    }
-                }
-            }
         }
     }
 }