fix: fix reconnection after opening socket asynchronously (#1253)

Closes socketio/socket.io#3358

lib/socket.js

@@ -104,7 +104,7 @@ Socket.prototype.connect = function () {
   if (this.connected) return this;
 
   this.subEvents();
-  this.io.open(); // ensure open
+  if (!this.io.reconnecting) this.io.open(); // ensure open
   if ('open' === this.io.readyState) this.onopen();
   this.emit('connecting');
   return this;

test/connection.js

@@ -433,6 +433,35 @@ describe('connection', function () {
 
       var socket = manager.socket('/invalid');
     });
+
+    it('should still try to reconnect twice after opening another socket asynchronously', function (done) {
+      var manager = io.Manager(
+        `http://localhost:9823`,
+        { reconnect: true, reconnectionAttempts: 2 }
+      );
+      var delay = Math.floor(manager.reconnectionDelay() * manager.randomizationFactor() * 0.5);
+      delay = Math.max(delay, 10);
+
+      var reconnects = 0;
+      var cb = function () {
+        reconnects++;
+      };
+
+      manager.on('reconnect_attempt', cb);
+
+      manager.on('reconnect_failed', function () {
+        expect(reconnects).to.be(2);
+        socket.disconnect();
+        manager.close();
+        done();
+      });
+
+      var socket = manager.socket('/room1');
+
+      setTimeout(() => {
+        manager.socket('/room2');
+      }, delay);
+    });
   }
 
   it('should emit date as string', function (done) {