add restart tests

1 files changed, 28 insertions, 5 deletions

diff --git a/src/transport/sim.rs b/src/transport/sim.rs
index e783743..2f167dc 100644
--- a/src/transport/sim.rs
+++ b/src/transport/sim.rs
@@ -83,6 +83,9 @@ struct NetInner {
     links: HashMap<(String, String), LinkParams>,
     down: HashSet<String>,
     inboxes: HashMap<String, mpsc::UnboundedSender<Delivery>>,
+    /// Per node, its current run (`restart`): what a transport of an earlier run sends
+    /// is lost, as from a process that is gone.
+    runs: HashMap<String, u64>,
     counts: NetCounts,
 }
 
@@ -109,6 +112,7 @@ impl SimNet {
                 links: HashMap::new(),
                 down: HashSet::new(),
                 inboxes: HashMap::new(),
+                runs: HashMap::new(),
                 counts: NetCounts::default(),
             })),
         }
@@ -121,15 +125,31 @@ impl SimNet {
     /// A transport for a new node `id` on this net.
     pub(crate) fn transport(&self, id: &str) -> Arc<SimTransport> {
         let (tx, rx) = mpsc::unbounded_channel();
-        let previous = self.lock().inboxes.insert(id.to_owned(), tx);
-        assert!(previous.is_none(), "node {id} is already on the net");
+        let run = {
+            let mut inner = self.lock();
+            let previous = inner.inboxes.insert(id.to_owned(), tx);
+            assert!(previous.is_none(), "node {id} is already on the net");
+            *inner.runs.entry(id.to_owned()).or_default()
+        };
         Arc::new(SimTransport {
             id: id.to_owned(),
+            run,
             net: self.clone(),
             inbox: tokio::sync::Mutex::new(Some(rx)),
         })
     }
 
+    /// Node `id`'s process is gone, as if it crashed: its transport neither sends nor
+    /// receives any more (messages on their way to it are lost), and [`transport`]
+    /// may give `id` a new one, for its next run.
+    ///
+    /// [`transport`]: Self::transport
+    pub(crate) fn restart(&self, id: &str) {
+        let mut inner = self.lock();
+        inner.inboxes.remove(id);
+        *inner.runs.entry(id.to_owned()).or_default() += 1;
+    }
+
     /// How links without their own parameters behave.
     pub(crate) fn set_default_link(&self, params: LinkParams) {
         self.lock().default_link = params;
@@ -157,12 +177,13 @@ impl SimNet {
     }
 
     /// Hands a message to the net: decides now whether and when it arrives.
-    fn send(&self, from: &str, message: &EncodedMessage) {
+    fn send(&self, from: &str, run: u64, message: &EncodedMessage) {
         let delays = {
             let mut guard = self.lock();
             let inner = &mut *guard;
             inner.counts.sent += 1;
-            if inner.down.contains(from) || inner.down.contains(&message.peer) {
+            let gone = inner.runs.get(from).is_some_and(|current| *current != run);
+            if gone || inner.down.contains(from) || inner.down.contains(&message.peer) {
                 inner.counts.lost += 1;
                 return;
             }
@@ -257,6 +278,8 @@ impl SimNet {
 /// are node IDs.
 pub(crate) struct SimTransport {
     id: String,
+    /// The run of its node it belongs to (`SimNet::restart`).
+    run: u64,
     net: SimNet,
     inbox: tokio::sync::Mutex<Option<mpsc::UnboundedReceiver<Delivery>>>,
 }
@@ -315,7 +338,7 @@ impl Transport for SimTransport {
     /// Always accepted: the net loses messages silently, like Mycelium once it has
     /// taken them.
     async fn send_encoded(&self, message: &EncodedMessage) -> Result<()> {
-        self.net.send(&self.id, message);
+        self.net.send(&self.id, self.run, message);
         Ok(())
     }