radicle: Announcer test adapting the replication target

The replication target should be constrained to the number of nodes to sync
with, if the original value exceeds that number.

crates/radicle/src/node/sync/announce.rs

@@ -579,7 +579,8 @@ mod test {
 
         let config = AnnouncerConfig::public(
             local,
-            ReplicationFactor::must_reach(5), // High target that we won't reach with preferred alone
+            // High target that we won't reach with preferred alone
+            ReplicationFactor::must_reach(5),
             preferred_seeds.clone(),
             BTreeSet::new(),
             unsynced,
@@ -929,6 +930,26 @@ mod test {
         }
     }
 
+    #[test]
+    fn announcer_adapts_target_to_reach() {
+        let local = arbitrary::gen::<NodeId>(0);
+        // Only 3 nodes available
+        let unsynced = arbitrary::set::<NodeId>(3..=3)
+            .into_iter()
+            .collect::<BTreeSet<_>>();
+
+        let config = AnnouncerConfig::public(
+            local,
+            ReplicationFactor::must_reach(5), // Want 5 but only have 3
+            BTreeSet::new(),
+            BTreeSet::new(),
+            unsynced.clone(),
+        );
+
+        let announcer = Announcer::new(config).unwrap();
+        assert_eq!(announcer.target().replicas().lower_bound(), 3);
+    }
+
     #[test]
     fn announcer_with_replication_factor_zero_and_preferred_seeds() {
         let local = arbitrary::gen::<NodeId>(0);