Add updated duplicate broadcast test (#18506)

gossip/src/cluster_info.rs

@@ -961,7 +961,7 @@ impl ClusterInfo {
         self.push_message(CrdsValue::new_signed(message, &self.keypair()));
     }
 
-    fn push_vote_at_index(&self, vote: Transaction, vote_index: u8) {
+    pub fn push_vote_at_index(&self, vote: Transaction, vote_index: u8) {
         assert!((vote_index as usize) < MAX_LOCKOUT_HISTORY);
         let self_pubkey = self.id();
         let now = timestamp();

gossip/src/gossip_service.rs

@@ -296,7 +296,7 @@ fn spy(
 
 /// Makes a spy or gossip node based on whether or not a gossip_addr was passed in
 /// Pass in a gossip addr to fully participate in gossip instead of relying on just pulls
-fn make_gossip_node(
+pub fn make_gossip_node(
     keypair: Keypair,
     entrypoint: Option<&SocketAddr>,
     exit: &Arc<AtomicBool>,