add restart tests

2 files changed, 47 insertions, 1 deletions

diff --git a/src/simtest/mod.rs b/src/simtest/mod.rs
index 81bddb5..61c81d1 100644
--- a/src/simtest/mod.rs
+++ b/src/simtest/mod.rs
@@ -144,6 +144,30 @@ impl Sim {
     }
 }
 
+impl Sim {
+    /// Restarts node `id`: its process is gone, as if it crashed (`SimNet::restart`:
+    /// what it still sends is lost), and a new one starts on the same ID, as
+    /// [`start_with`](Self::start_with) starts one. Nothing carries over but what
+    /// `adjust` gives it (its node key, under the identity layer, by its name).
+    pub(crate) fn restart_with(
+        &self,
+        id: &str,
+        seeds: &[&str],
+        start: Start,
+        adjust: impl FnOnce(&mut NodeConfig),
+    ) -> AppState {
+        {
+            let mut nodes = self.nodes.lock().unwrap();
+            for (_, old) in nodes.iter().filter(|(name, _)| name == id) {
+                old.closing.send_replace(true);
+            }
+            nodes.retain(|(name, _)| name != id);
+        }
+        self.net.restart(id);
+        self.start_with(id, seeds, start, adjust)
+    }
+}
+
 /// Logs to the test output if `RUST_LOG` is set.
 fn init_logging() {
     if std::env::var_os("RUST_LOG").is_some() {
diff --git a/src/simtest/timing.rs b/src/simtest/timing.rs
index fd76a17..daa588f 100644
--- a/src/simtest/timing.rs
+++ b/src/simtest/timing.rs
@@ -1,5 +1,5 @@
 //! The timing rules of `peers.md` on whole nodes: joining and converging, dormancy and
-//! return, and late messages that must not undo what newer ones said.
+//! return, a restart, and late messages that must not undo what newer ones said.
 
 use std::time::Duration;
 
@@ -46,6 +46,28 @@ async fn three_nodes_join_and_converge() {
     }
 }
 
+/// A node that restarts without a document file (its process gone, a new one on the
+/// same ID) joins again and gets the document; what its earlier run sends on is lost.
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn restarted_node_joins_again() {
+    let sim = Sim::new(9);
+    let a = sim.start("a", &[], Start::Genesis);
+    let b = sim.start("b", &["a"], Start::Join);
+    sim.wait_ready(&[&a, &b], SOON).await;
+    write(&a, "before", json!(1)).await;
+    sim.wait_converged(&[&a, &b], SOON).await;
+
+    let b = sim.restart_with("b", &["a"], Start::Join, |_| {});
+    sim.wait_ready(&[&b], SOON).await;
+    let b = &b;
+    sim.wait_until("b has the document again", SOON, move || async move {
+        read(b, "before").await == Some(json!(1))
+    })
+    .await;
+    write(b, "after", json!(2)).await;
+    sim.wait_converged(&[&a, b], SOON).await;
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
 async fn converges_with_duplicated_and_reordered_messages() {
     let sim = Sim::new(2);