replication: fix test build drift (Heartbeat.members, LeaderNode::new, WalWriter) (#5)

The wolfscale lib-test target failed to compile (5 errors) because test code had
drifted from the current lib API. The library itself built fine, so this was
only caught when running `cargo test`.

- protocol.rs: `Message::Heartbeat` gained a `members: Vec<(String, String)>`
  field; add it to the test constructor and ignore it in the match pattern.
- leader.rs: `LeaderNode::new` gained an 8th `executor: Option<Arc<MariaDbExecutor>>`
  argument; pass `None` in the test.
- follower.rs: qualify `WalWriter` as `crate::wal::WalWriter` in the test (the
  type was never imported into this module).

No production code changed — test-only fixes. `cargo test`: 44 passed.

Co-authored-by: Paul C <paulc@wolf.uk.com>

Author: wolfsoftwaresystemsltd

Cargo.lock

@@ -711,7 +711,7 @@ mod tests {
         let dir = tempdir().unwrap();
         let (tx, _rx) = mpsc::channel(100);
 
-        let wal_writer = WalWriter::new(
+        let wal_writer = crate::wal::WalWriter::new(
             dir.path().to_path_buf(),
             test_wal_config(),
             "follower".to_string(),

src/replication/follower.rs

@@ -741,6 +741,7 @@ mod tests {
             cluster,
             ReplicationConfig::default(),
             tx,
+            None,
         );
     }
 }

src/replication/leader.rs

@@ -285,13 +285,14 @@ mod tests {
             term: 1,
             leader_id: "node-1".to_string(),
             commit_lsn: 100,
+            members: vec![],
         };
 
         let bytes = msg.serialize().unwrap();
         let restored = Message::deserialize(&bytes).unwrap();
 
         match restored {
-            Message::Heartbeat { term, leader_id, commit_lsn } => {
+            Message::Heartbeat { term, leader_id, commit_lsn, .. } => {
                 assert_eq!(term, 1);
                 assert_eq!(leader_id, "node-1");
                 assert_eq!(commit_lsn, 100);