Use specific boolean for a leaf test instead of using leafNodeEnabled

A test TestJetStreamClusterLeafNodeSPOFMigrateLeaders was added at
some point that needed the remotes to stop (re)connecting. It made
use of existing leafNodeEnabled that was used for GW/Leaf interest
propagation races to disable the reconnect, but that may not be
the best approach since it could affect users embedding servers
and adding leafnodes "dynamically".

So this PR introduced a specific boolean specific for that test.

Signed-off-by: Ivan Kozlovic <ivan@synadia.com>

server/jetstream_helpers_test.go

@@ -951,7 +951,7 @@ func (s *Server) closeAndDisableLeafnodes() {
 		leafs = append(leafs, ln)
 	}
 	// Disable leafnodes for now.
-	s.leafNodeEnabled = false
+	s.leafDisableConnect = true
 	s.mu.Unlock()
 
 	for _, ln := range leafs {

server/leafnode.go

@@ -495,12 +495,13 @@ func (s *Server) connectToRemoteLeafNode(remote *leafNodeCfg, firstConnect bool)
 			if url != rURL.Host {
 				ipStr = fmt.Sprintf(" (%s)", url)
 			}
-			if s.isLeafNodeEnabled() {
-				s.Debugf("Trying to connect as leafnode to remote server on %q%s", rURL.Host, ipStr)
-				conn, err = natsDialTimeout("tcp", url, dialTimeout)
-			} else {
+			// Some test may want to disable remotes from connecting
+			if s.isLeafConnectDisabled() {
 				s.Debugf("Will not attempt to connect to remote server on %q%s, leafnodes currently disabled", rURL.Host, ipStr)
 				err = ErrLeafNodeDisabled
+			} else {
+				s.Debugf("Trying to connect as leafnode to remote server on %q%s", rURL.Host, ipStr)
+				conn, err = natsDialTimeout("tcp", url, dialTimeout)
 			}
 		}
 		if err != nil {
@@ -569,10 +570,10 @@ func (s *Server) checkJetStreamMigrate(remote *leafNodeCfg) {
 }
 
 // Helper for checking.
-func (s *Server) isLeafNodeEnabled() bool {
+func (s *Server) isLeafConnectDisabled() bool {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
-	return s.leafNodeEnabled
+	return s.leafDisableConnect
 }
 
 // Save off the tlsName for when we use TLS and mix hostnames and IPs. IPs usually

server/server.go

@@ -164,6 +164,7 @@ type Server struct {
 	leafRemoteCfgs     []*leafNodeCfg
 	leafRemoteAccounts sync.Map
 	leafNodeEnabled    bool
+	leafDisableConnect bool // Used in test only
 
 	quitCh           chan struct{}
 	startupComplete  chan struct{}