Fix sending of WebSocket messages enqueued during a disconnection

Any WebSocket messages submitted whilst the WS is disconnected
should be re-sent when the WS reconnects.

This was broken because upon a disconnect, the 'onclose'
event handler first synchronously called reconnect(), resulting
in a new WebSocket instance being created and then set 'socket'
to null. This caused an error in sendMessages() after the 'onopen'
event was triggered.

Fix the problem by not using a null 'socket' var to represent
a disconnected socket. Instead just use the WebSocket's readyState
property.

h/static/scripts/test/websocket-test.js

@@ -33,6 +33,20 @@ describe('websocket wrapper', function () {
     assert.notEqual(fakeSocket, initialSocket);
   });
 
+  it('should send queued messages after a reconnect', function () {
+    // simulate WebSocket setup and initial connection
+    var socket = new Socket('ws://test:1234');
+    fakeSocket.onopen({});
+
+    // simulate abnormal disconnection
+    fakeSocket.onclose({code: 1006});
+
+    // enqueue a message and check that it is sent after the WS reconnects
+    socket.send({aKey: 'aValue'});
+    fakeSocket.onopen({});
+    assert.calledWith(fakeSocket.send, '{"aKey":"aValue"}');
+  });
+
   it('should not reconnect after a normal disconnection', function () {
     var socket = new Socket('ws://test:1234');
     socket.close();

h/static/scripts/websocket.js

@@ -22,7 +22,7 @@ function Socket(url) {
   // queue of JSON objects which have not yet been submitted
   var messageQueue = [];
 
-  // the current WebSocket instance or null if disconnected
+  // the current WebSocket instance
   var socket;
 
   function sendMessages() {
@@ -58,7 +58,6 @@ function Socket(url) {
             connectOperation.retry(new Error(event.reason));
           }
         }
-        socket = null;
         self.emit('close', event);
       };
 
@@ -74,10 +73,6 @@ function Socket(url) {
 
   /** Close the underlying WebSocket connection */
   this.close = function () {
-    if (!socket) {
-      console.error('Socket.close() called before socket was connected');
-      return;
-    }
     socket.close();
   };
 
@@ -94,7 +89,7 @@ function Socket(url) {
 
   /** Returns true if the WebSocket is currently connected. */
   this.isConnected = function () {
-    return socket && socket.readyState === WebSocket.OPEN;
+    return socket.readyState === WebSocket.OPEN;
   };
 
   // establish the initial connection