fix: merge Engine.IO options

So that the following example:

```js
const io = require('socket.io')({
  pingTimeout: 10000
});

io.listen(3000);
```

behaves the same as:

```js
const io = require('socket.io')(3000, {
  pingTimeout: 10000
});
```

Before this change, the options in the first example were not forwarded
to the Engine.IO constructor, which is not really intuitive.

The previous syntax (which is still valid):

```js
const io = require('socket.io')();

io.listen(3000, {
  pingTimeout: 10000
});
```

lib/index.ts

@@ -169,6 +169,7 @@ export class Server extends EventEmitter {
  > = new Map();
  private _adapter: any;
  private _serveClient: boolean;
+ private opts: Partial<EngineOptions>;
  private eio;
  private engine;
  private _path: string;
@@ -203,7 +204,8 @@ export class Server extends EventEmitter {
  this.encoder = new this._parser.Encoder();
  this.adapter(opts.adapter || Adapter);
  this.sockets = this.of("/");
- if (srv) this.attach(srv, opts);
+ this.opts = opts;
+ if (srv) this.attach(srv);
  }
 
  /**
@@ -357,6 +359,8 @@ export class Server extends EventEmitter {
  srv.listen(port);
  }
 
+ // merge the options passed to the Socket.IO server
+ Object.assign(opts, this.opts);
  // set engine.io path to `/socket.io`
  opts.path = opts.path || this._path;
 

test/socket.io.ts

@@ -138,6 +138,24 @@ describe("socket.io", () => {
  done();
  });
  });
+
+ it("should work with #attach (and merge options)", () => {
+ const srv = createServer((req, res) => {
+ res.writeHead(404);
+ res.end();
+ });
+ const server = new Server({
+ pingTimeout: 6000
+ });
+ server.attach(srv, {
+ pingInterval: 24000
+ });
+ // @ts-ignore
+ expect(server.eio.opts.pingTimeout).to.eql(6000);
+ // @ts-ignore
+ expect(server.eio.opts.pingInterval).to.eql(24000);
+ server.close();
+ });
  });
 
  describe("port", () => {