Handle single-node Raft leaders during construction again

Author: erikgrinaker

Diff for: src/raft/node/follower.rs

@@ -59,7 +59,7 @@ impl RoleNode<Follower> {
 
     /// Transforms the node into a candidate, by campaigning for leadership in a
     /// new term.
-    fn become_candidate(mut self) -> Result<RoleNode<Candidate>> {
+    pub(super) fn become_candidate(mut self) -> Result<RoleNode<Candidate>> {
         // Abort any forwarded requests. These must be retried with new leader.
         self.abort_forwarded()?;
 
@@ -232,11 +232,6 @@ impl RoleNode<Follower> {
     pub fn tick(mut self) -> Result<Node> {
         self.assert()?;
 
-        // If there are no peers, transition to leader immediately.
-        if self.peers.is_empty() {
-            return Ok(self.become_candidate()?.become_leader()?.into());
-        }
-
         self.role.leader_seen += 1;
         if self.role.leader_seen >= self.role.election_timeout {
             return Ok(self.become_candidate()?.into());

Diff for: src/raft/node/mod.rs

@@ -70,15 +70,20 @@ impl Node {
         tokio::spawn(driver.drive(state));
 
         let (term, voted_for) = log.get_term()?;
-        Ok(Node::Follower(RoleNode {
+        let node = RoleNode {
             id,
             peers,
             term,
             log,
             node_tx,
             state_tx,
             role: Follower::new(None, voted_for),
-        }))
+        };
+        if node.peers.is_empty() {
+            // If there are no peers, become leader immediately.
+            return Ok(node.become_candidate()?.become_leader()?.into());
+        }
+        Ok(node.into())
     }
 
     /// Returns the node ID.
@@ -460,7 +465,7 @@ mod tests {
 
     #[tokio::test]
     async fn new_single() -> Result<()> {
-        let (node_tx, _) = mpsc::unbounded_channel();
+        let (node_tx, _node_rx) = mpsc::unbounded_channel();
         let node = Node::new(
             1,
             HashSet::new(),

Diff for: tests/client/mod.rs

@@ -125,11 +125,11 @@ async fn status() -> Result<()> {
                 server: 1,
                 leader: 1,
                 term: 1,
-                node_last_index: vec![(1, 26)].into_iter().collect(),
-                commit_index: 26,
-                apply_index: 26,
+                node_last_index: [(1, 27)].into(),
+                commit_index: 27,
+                apply_index: 27,
                 storage: "bitcask".into(),
-                storage_size: 1313,
+                storage_size: 1324,
             },
             mvcc: mvcc::Status {
                 versions: 1,