public function testEventBasedAdding()
 {
     $additionalMessageKeys = $this->additionalMessageKeys;
     Event::listen('JsLocalization.registerMessages', function () use($additionalMessageKeys) {
         JsLocalizationHelper::addMessagesToExport($additionalMessageKeys);
     });
     $this->assertEquals(array(), JsLocalizationHelper::getAdditionalMessages());
     JsLocalizationHelper::triggerRegisterMessages();
     $this->assertEquals($this->additionalMessageKeysFlat, JsLocalizationHelper::getAdditionalMessages());
     $this->addTestMessage('en', 'another', 'Another test text.');
     Event::listen('JsLocalization.registerMessages', function () {
         JsLocalizationHelper::addMessagesToExport(array('another'));
     });
     JsLocalizationHelper::triggerRegisterMessages();
     $this->assertEquals(array_merge($this->additionalMessageKeysFlat, array('another')), JsLocalizationHelper::getAdditionalMessages());
 }