fix: allow a single node cluster to scale out to a multiple nodes clu…

…ster

Signed-off-by: Phoeniix Zhao <[email protected]>

curp/src/server/raw_curp/mod.rs

@@ -1246,10 +1246,7 @@ impl<C: Command, RC: RoleChange> RawCurp<C, RC> {
         let mut all_nodes = HashSet::new();
         all_nodes.extend(config.voters());
         all_nodes.extend(&config.learners);
-        if statuses_ids.len() < 3
-            || all_nodes != statuses_ids
-            || !config.voters().is_disjoint(&config.learners)
-        {
+        if all_nodes != statuses_ids || !config.voters().is_disjoint(&config.learners) {
             return Err(CurpError::invalid_config());
         }
         Ok(())

curp/src/server/raw_curp/tests.rs

@@ -845,19 +845,6 @@ fn remove_non_exists_node_should_return_node_not_exists_error() {
     assert!(matches!(resp, Err(CurpError::NodeNotExists(()))));
 }
 
-#[traced_test]
-#[test]
-fn remove_node_should_return_invalid_config_error_when_nodes_count_less_than_3() {
-    let curp = {
-        let exe_tx = MockCEEventTxApi::<TestCommand>::default();
-        Arc::new(RawCurp::new_test(3, exe_tx, mock_role_change()))
-    };
-    let follower_id = curp.cluster().get_id_by_name("S1").unwrap();
-    let changes = vec![ConfChange::remove(follower_id)];
-    let resp = curp.check_new_config(&changes);
-    assert!(matches!(resp, Err(CurpError::InvalidConfig(()))));
-}
-
 #[traced_test]
 #[test]
 fn update_node_should_update_the_address_of_node() {

curp/tests/it/server.rs

@@ -386,23 +386,6 @@ async fn propose_update_node_should_success() {
     assert!(member.is_some_and(|m| m.addrs == ["new_addr"]));
 }
 
-#[tokio::test(flavor = "multi_thread")]
-#[abort_on_panic]
-async fn propose_remove_node_should_failed_when_cluster_nodes_equals_to_three() {
-    init_logger();
-
-    let group = CurpGroup::new(3).await;
-    let client = group.new_client().await;
-
-    let node_id = group.nodes.keys().next().copied().unwrap();
-    let changes = vec![ConfChange::remove(node_id)];
-    let res = client.propose_conf_change(changes).await;
-    assert!(matches!(
-        CurpError::from(res.unwrap_err()),
-        CurpError::InvalidConfig(())
-    ));
-}
-
 #[tokio::test(flavor = "multi_thread")]
 #[abort_on_panic]
 async fn shutdown_rpc_should_shutdown_the_cluster_when_client_has_wrong_leader() {