make subscribe.onDone foolproof

src/kuzzleSubscribeResult.js

@@ -4,14 +4,22 @@
  */
 function KuzzleSubscribeResult() {
   this.cbs = [];
+  this.error = null;
+  this.room = null;
 }
 
 /**
  * Registers a callback to be called with a subscription result
  * @param {Function} cb
  */
 KuzzleSubscribeResult.prototype.onDone = function (cb) {
-  this.cbs.push(cb);
+  if (this.error || this.room) {
+    cb(this.error, this.room);
+  }
+  else {
+    this.cbs.push(cb);
+  }
+
   return this;
 };
 
@@ -22,6 +30,9 @@ KuzzleSubscribeResult.prototype.onDone = function (cb) {
  * @param {KuzzleRoom} room
  */
 KuzzleSubscribeResult.prototype.done = function (error, room) {
+  this.error = error;
+  this.room = room;
+
   this.cbs.forEach(function (cb) {
     cb(error, room);
   });

test/kuzzleSubscribeResult/kuzzleSubscribeResult.test.js

@@ -34,6 +34,8 @@ describe('KuzzleSubscribeResult object', function () {
         count++;
         should(err).be.eql(foo);
         should(res).be.eql(bar);
+        should(ksr.error).be.eql(err);
+        should(ksr.room).be.eql(res);
         if (count === 3) {
           done();
         }
@@ -49,5 +51,22 @@ describe('KuzzleSubscribeResult object', function () {
 
     ksr.done(foo, bar);
   });
+
+  it('should invoke the provided callback directly if Kuzzle response is already stored', function (done) {
+    var
+      cb = function (err, res) {
+        should(err).be.eql('foo');
+        should(res).be.eql('bar');
+        should(ksr.cbs).be.empty();
+        done();
+      };
+
+    this.timeout(50);
+
+    ksr.error = 'foo';
+    ksr.room = 'bar';
+
+    ksr.onDone(cb);
+  });
 });