diff -r 000000000000 -r 6474c204b198 browser/components/tabview/test/browser_tabview_bug600645.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/tabview/test/browser_tabview_bug600645.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,80 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * This file tests that, when there is an app tab that references an invalid
+ * favicon, the default favicon appears the group app tab tray, instead of an
+ * empty image that would not be visible.
+ */
+
+const fi = Cc["@mozilla.org/browser/favicon-service;1"].
+           getService(Ci.nsIFaviconService);
+
+let newTab;
+
+function test() {
+  waitForExplicitFinish();
+
+  newTab = gBrowser.addTab();
+
+  showTabView(function() {
+    let cw = TabView.getContentWindow();
+    whenAppTabIconAdded(cw.GroupItems.groupItems[0], onTabPinned);
+    gBrowser.pinTab(newTab);
+  })
+}
+
+function onTabPinned() {
+  let contentWindow = TabView.getContentWindow();
+  is(contentWindow.GroupItems.groupItems.length, 1, 
+     "There is one group item on startup");
+
+  let groupItem = contentWindow.GroupItems.groupItems[0];
+  let icon = contentWindow.iQ(".appTabIcon", groupItem.$appTabTray)[0];
+  let $icon = contentWindow.iQ(icon);
+
+  is($icon.data("xulTab"), newTab, 
+     "The app tab icon has the right tab reference")
+  // check to see whether it's showing the default one or not.
+  is($icon.attr("src"), fi.defaultFavicon.spec,
+     "The icon is showing the default fav icon for blank tab");
+
+  let errorHandler = function(event) {
+    newTab.removeEventListener("error", errorHandler, false);
+
+    // since the browser code and test code are invoked when an error event is 
+    // fired, a delay is used here to avoid the test code run before the browser 
+    // code.
+    executeSoon(function() {
+      let iconSrc = $icon.attr("src");
+
+      // with moz-anno:favicon automatically redirects to the default favIcon 
+      // if the given url is invalid
+      ok(iconSrc.startsWith("moz-anno:favicon:"),
+         "The icon url starts with moz-anno:favicon so the default fav icon would be displayed");
+
+      // At this point, as an additional integrity check we could also verify
+      // that the iconSrc URI does not have any associated favicon data.  This
+      // kind of check, however, is not easily supported by the asynchronous
+      // favicon API.  Fortunately, the fact that we received the error event
+      // already indicates that the original favicon was not available.
+      // Morevover, since we are using a "moz-anno:favicon:" URI, we know that
+      // we'll not display an empty icon, but the default favicon.
+
+      // clean up
+      gBrowser.removeTab(newTab);
+      let endGame = function() {
+        window.removeEventListener("tabviewhidden", endGame, false);
+
+        ok(!TabView.isVisible(), "Tab View is hidden");
+        finish();
+      }
+      window.addEventListener("tabviewhidden", endGame, false);
+      TabView.toggle();
+    });
+  };
+  newTab.addEventListener("error", errorHandler, false);
+
+  newTab.linkedBrowser.loadURI(
+    "http://mochi.test:8888/browser/browser/components/tabview/test/test_bug600645.html");
+}