test: address review gaps in timing and dynamic targets

crates/irtt-server/tests/protocol_contracts.rs

@@ -321,39 +321,50 @@ fn negotiated_timestamp_modes_emit_only_the_selected_fields_in_order() {
 fn duration_close_waits_for_rate_allowance_after_the_deadline() {
     let refill = Duration::from_secs(4);
     let maximum = Duration::from_millis(1);
-    let mut server = ServerCore::new(
-        ServerConfig::default()
-            .with_min_send_interval(refill)
-            .with_burst_allowance(1)
-            .with_idle_timeout(Duration::MAX)
-            .with_max_test_duration(maximum),
-    );
-    let opened = open(
-        &mut server,
-        &Params {
-            received_stats: ReceivedStats::Both,
-            ..Params::with_protocol_defaults()
-        },
-    );
-    let first = echo(&mut server, &opened, 0).unwrap();
-    assert_eq!(first.flags & FLAG_CLOSE, 0);
-    thread::sleep(maximum + Duration::from_secs(2));
-    assert!(
-        echo(&mut server, &opened, 63).is_none(),
-        "exhausted allowance must suppress the deadline-crossing reply"
-    );
-    assert_eq!(
-        server.session_count(),
-        1,
-        "rate refusal must not release the session"
-    );
-    thread::sleep(refill);
-    let closed = echo(&mut server, &opened, 1).unwrap();
-    assert_ne!(closed.flags & FLAG_CLOSE, 0);
-    assert_eq!(closed.sequence, 1);
-    assert_eq!(closed.recv_count, Some(2));
-    assert_eq!(closed.recv_window, Some(3));
-    assert_eq!(server.session_count(), 0);
+    for _ in 0..3 {
+        let mut server = ServerCore::new(
+            ServerConfig::default()
+                .with_min_send_interval(refill)
+                .with_burst_allowance(1)
+                .with_idle_timeout(Duration::MAX)
+                .with_max_test_duration(maximum),
+        );
+        let started = Instant::now();
+        let opened = open(
+            &mut server,
+            &Params {
+                received_stats: ReceivedStats::Both,
+                ..Params::with_protocol_defaults()
+            },
+        );
+        let first = echo(&mut server, &opened, 0).unwrap();
+        assert_eq!(first.flags & FLAG_CLOSE, 0);
+        thread::sleep(maximum + Duration::from_secs(2));
+        let refused = echo(&mut server, &opened, 63);
+        // Include open/setup and the request itself in the elapsed bound. If the
+        // scheduler carried us past refill, the reply may legitimately close.
+        if started.elapsed() >= refill {
+            continue;
+        }
+        assert!(
+            refused.is_none(),
+            "exhausted allowance must suppress the deadline-crossing reply"
+        );
+        assert_eq!(
+            server.session_count(),
+            1,
+            "rate refusal must not release the session"
+        );
+        thread::sleep(refill);
+        let closed = echo(&mut server, &opened, 1).unwrap();
+        assert_ne!(closed.flags & FLAG_CLOSE, 0);
+        assert_eq!(closed.sequence, 1);
+        assert_eq!(closed.recv_count, Some(2));
+        assert_eq!(closed.recv_window, Some(3));
+        assert_eq!(server.session_count(), 0);
+        return;
+    }
+    panic!("scheduler crossed the refill boundary in all three fresh sessions");
 }
 
 #[test]