1 files changed, 52 insertions, 2 deletions
diff --git a/src/simtest/reach.rs b/src/simtest/reach.rs
index eca0a47..e538679 100644
--- a/src/simtest/reach.rs
+++ b/src/simtest/reach.rs
@@ -129,7 +129,7 @@ async fn pulled_changes_go_along_their_writers_trees() {
     let x = sim.start_on_with("x", &["sim"], &["b"], Start::Join, slow);
     sim.wait_ready(&[&b, &c, &d, &x], SOON).await;
     sim.wait_converged(&[&b, &c, &d, &x], SOON * 2).await;
-    let (b, c, x) = (&b, &c, &x);
+    let (b, c, d, x) = (&b, &c, &d, &x);
     let writer = topology::pair_key(x.local_id());
     sim.wait_until("c under b in x's tree", SOON, move || async move {
         tree::children(b, writer).await == [c.local_id().to_owned()]
@@ -138,13 +138,63 @@ async fn pulled_changes_go_along_their_writers_trees() {
 
     let (c_pulls, _) = counted(c);
     let (_, b_forwards) = counted(b);
+    // What b and c send and receive from now on, to show should c pull.
+    b.traffic.log.watch(true);
+    c.traffic.log.watch(true);
     super::write(x, "y", serde_json::json!(1)).await;
+    let written = super::heads(x).await;
     sim.wait_until("c has x's write", SOON, move || async move {
         super::read(c, "y").await == Some(serde_json::json!(1))
     })
     .await;
     assert!(counted(b).1 > b_forwards, "b passed it on along x's tree");
-    assert_eq!(counted(c).0, c_pulls, "c pulled nothing");
+    assert_eq!(
+        counted(c).0,
+        c_pulls,
+        "c pulled nothing; x's write is {written:?}; what b and c sent and received meanwhile:\n{}",
+        logged(
+            &[("b", b), ("c", c)],
+            &[("b", b), ("c", c), ("d", d), ("x", x)]
+        )
+    );
+}
+
+/// What `nodes` sent and received, as their logs kept them (`MessageLog`), in order,
+/// peers by their names in `names`: STATUSes and SYNCs written out, the others by type.
+fn logged(nodes: &[(&str, &AppState)], names: &[(&str, &AppState)]) -> String {
+    let name = |id: &str| {
+        names
+            .iter()
+            .find(|(_, node)| node.local_id() == id)
+            .map_or(id.to_owned(), |(name, _)| (*name).to_owned())
+    };
+    let mut lines: Vec<(u64, String)> = Vec::new();
+    for (node_name, node) in nodes {
+        for logged in node.traffic.log.after(0, 1000) {
+            let text = if logged.kind.starts_with("STATUS") || logged.kind == "SYNC" {
+                format!("\n{}", logged.text)
+            } else {
+                String::new()
+            };
+            lines.push((
+                logged.at,
+                format!(
+                    "{} {node_name} {} {} {} {}{text}",
+                    logged.at,
+                    logged.way,
+                    logged.kind,
+                    if logged.way == "sent" { "to" } else { "from" },
+                    name(&logged.peer),
+                ),
+            ));
+        }
+    }
+    lines.sort_by_key(|(at, _)| *at);
+    lines
+        .into_iter()
+        .map(|(_, line)| line)
+        .collect::<Vec<_>>()
+        .join("\n")
 }
 
 /// x, b and c, nothing between x and c: x's changes reach c through b, along x's tree.