Properly shutdown testing http server

It turned out that server.close() does not shutdown server but
stops it from accepting *new* connections.

It's our responsibility to destroy all the current connections,
if any.

test/SimpleServer.js

@@ -42,19 +42,35 @@ class SimpleServer {
    */
   constructor(dirPath, port) {
     this._server = http.createServer(this._onRequest.bind(this));
+    this._server.on('connection', socket => this._onSocket(socket));
     this._wsServer = new WebSocketServer({server: this._server});
     this._wsServer.on('connection', this._onWebSocketConnection.bind(this));
     this._server.listen(port);
     this._dirPath = dirPath;
 
+    /** @type {!Set<!net.Socket>} */
+    this._sockets = new Set();
+
     /** @type {!Map<string, function(!IncomingMessage, !ServerResponse)>} */
     this._routes = new Map();
     /** @type {!Map<string, !Promise>} */
     this._requestSubscribers = new Map();
   }
 
-  stop() {
-    this._server.close();
+  _onSocket(socket) {
+    this._sockets.add(socket);
+    socket.once('close', () => this._sockets.delete(socket));
+  }
+
+  /**
+   * @return {!Promise}
+   */
+  async stop() {
+    this.reset();
+    for (let socket of this._sockets)
+      socket.destroy();
+    this._sockets.clear();
+    await new Promise(x => this._server.close(x));
   }
 
   /**

test/test.js

@@ -36,10 +36,10 @@ describe('Puppeteer', function() {
     GoldenUtils.removeOutputDir();
   }));
 
-  afterAll(function() {
-    server.stop();
+  afterAll(SX(async function() {
+    await server.stop();
     browser.close();
-  });
+  }));
 
   beforeEach(SX(async function() {
     page = await browser.newPage();
@@ -105,7 +105,7 @@ describe('Puppeteer', function() {
   });
 
   describe('Page.injectFile', function() {
-    it('should fail when navigating to bad url', SX(async function() {
+    it('should work', SX(async function() {
       const helloPath = path.join(__dirname, './assets/injectedfile.js');
       await page.injectFile(helloPath);
       const result = await page.evaluate(() => __injected);