add failing nullification check

Author: patrick-ogrady

consensus/src/threshold_simplex/mocks/supervisor.rs

@@ -42,6 +42,7 @@ pub struct Supervisor<P: Array, D: Digest> {
     nullify_namespace: Vec<u8>,
     finalize_namespace: Vec<u8>,
 
+    pub leaders: Arc<Mutex<HashMap<View, P>>>,
     pub notarizes: Arc<Mutex<Participation<D, P>>>,
     pub nullifies: Arc<Mutex<HashMap<View, HashSet<P>>>>,
     pub finalizes: Arc<Mutex<Participation<D, P>>>,
@@ -68,6 +69,7 @@ impl<P: Array, D: Digest> Supervisor<P, D> {
             notarize_namespace: notarize_namespace(&cfg.namespace),
             nullify_namespace: nullify_namespace(&cfg.namespace),
             finalize_namespace: finalize_namespace(&cfg.namespace),
+            leaders: Arc::new(Mutex::new(HashMap::new())),
             notarizes: Arc::new(Mutex::new(HashMap::new())),
             nullifies: Arc::new(Mutex::new(HashMap::new())),
             finalizes: Arc::new(Mutex::new(HashMap::new())),
@@ -121,7 +123,13 @@ impl<P: Array, D: Digest> TSu for Supervisor<P, D> {
         };
         let seed = seed.serialize();
         let index = modulo(&seed, closest.len() as u64);
-        Some(closest[index as usize].clone())
+        let leader = closest[index as usize].clone();
+        self.leaders
+            .lock()
+            .unwrap()
+            .entry(index)
+            .or_insert(leader.clone());
+        Some(leader)
     }
 
     fn identity(&self, index: Self::Index) -> Option<&Self::Identity> {

consensus/src/threshold_simplex/mod.rs

@@ -164,9 +164,8 @@ pub mod mocks;
 
 #[cfg(test)]
 mod tests {
-    use crate::Monitor;
-
     use super::*;
+    use crate::Monitor;
     use commonware_cryptography::{bls12381::dkg::ops, Ed25519, Sha256, Signer};
     use commonware_macros::{select, test_traced};
     use commonware_p2p::simulated::{Config, Link, Network, Oracle, Receiver, Sender};
@@ -1070,6 +1069,28 @@ mod tests {
                         }
                     }
                 }
+
+                // Identify offline views
+                let mut offline_views = Vec::new();
+                {
+                    let leaders = supervisor.leaders.lock().unwrap();
+                    for (view, leader) in leaders.iter() {
+                        if leader == offline {
+                            offline_views.push(*view);
+                        }
+                    }
+                }
+
+                // Ensure nullifies collected for offline node
+                {
+                    let nullifies = supervisor.nullifies.lock().unwrap();
+                    for view in offline_views.iter() {
+                        let nullifies = nullifies.get(view).unwrap();
+                        if nullifies.len() < threshold as usize {
+                            panic!("view: {}", view);
+                        }
+                    }
+                }
             }
         });
     }