1 files changed, 48 insertions, 0 deletions
diff --git a/src/simtest/timing.rs b/src/simtest/timing.rs
index e4981dd..4247090 100644
--- a/src/simtest/timing.rs
+++ b/src/simtest/timing.rs
@@ -239,6 +239,53 @@ async fn is_dormant(node: &AppState, other: &str) -> bool {
         == Some(true)
 }
 
+/// R27: a resent HELLO (its reply was lost) or a late copy of one doesn't reset the
+/// session it opened; only a new handshake does.
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn resent_hello_keeps_the_session() {
+    let sim = Sim::new(8);
+    let a = sim.start("a", &[], Start::Genesis);
+    let b = sim.start("b", &["a"], Start::Join);
+    let (a, b) = (&a, &b);
+    sim.wait_ready(&[a, b], SOON).await;
+    write(a, "data", json!(1)).await;
+    sim.wait_converged(&[a, b], SOON).await;
+    let opened = move || async move { peer(a, "b", |p| p.sync.has_opened()).await == Some(true) };
+    sim.wait_until("a has heard b's heads", SOON, opened).await;
+
+    let (run, handshake) = peer(a, "b", |p| p.last_hello).await.unwrap().unwrap();
+    assert_eq!(run, b.run_id);
+    let (epoch, epoch_seq) = b.epoch_stamp().await;
+    let swarm_id = b.swarm_id().await;
+    let hello = |handshake| {
+        ParsedMessage::Hello(HelloRequest {
+            swarm_id: swarm_id.clone(),
+            epoch,
+            epoch_seq,
+            auth: Vec::new(),
+            ready: true,
+            run_id: run,
+            handshake,
+        })
+    };
+    for repeated in [handshake, handshake.saturating_sub(1)] {
+        sim.net.inject("b", "a", &hello(repeated)).await.unwrap();
+        assert!(opened().await, "HELLO {repeated} reset the session");
+        assert_eq!(
+            peer(a, "b", |p| p.last_hello).await.unwrap(),
+            Some((run, handshake))
+        );
+    }
+    sim.net
+        .inject("b", "a", &hello(handshake + 1))
+        .await
+        .unwrap();
+    assert_eq!(
+        peer(a, "b", |p| p.last_hello).await.unwrap(),
+        Some((run, handshake + 1))
+    );
+}
+
 /// R17: a message sent before the peer's last epoch change and delivered late doesn't
 /// flip the epoch we recorded for it back; a new run of the peer starts its count over.
 /// The peer is a "ghost" whose messages are injected, so their order is the test's.
@@ -261,6 +308,7 @@ async fn late_epoch_does_not_flip_a_peers_epoch() {
             auth: Vec::new(),
             ready: true,
             run_id: run,
+            handshake: 1,
         })
     };
     let ping = |epoch: Epoch, epoch_seq: u32| {