diff -r 000000000000 -r 6474c204b198 browser/base/content/test/general/browser_bug491431.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/general/browser_bug491431.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+let testPage = "data:text/plain,test bug 491431 Page";
+
+function test() {
+  waitForExplicitFinish();
+
+  let newWin, tabA, tabB;
+
+  // test normal close
+  tabA = gBrowser.addTab(testPage);
+  gBrowser.tabContainer.addEventListener("TabClose", function(aEvent) {
+    gBrowser.tabContainer.removeEventListener("TabClose", arguments.callee, true);
+    ok(!aEvent.detail, "This was a normal tab close");
+
+    // test tab close by moving
+    tabB = gBrowser.addTab(testPage);
+    gBrowser.tabContainer.addEventListener("TabClose", function(aEvent) {
+      gBrowser.tabContainer.removeEventListener("TabClose", arguments.callee, true);
+      executeSoon(function() {
+        ok(aEvent.detail, "This was a tab closed by moving");
+
+        // cleanup
+        newWin.close();
+        executeSoon(finish);
+      });
+    }, true);
+    newWin = gBrowser.replaceTabWithWindow(tabB);
+  }, true);
+  gBrowser.removeTab(tabA);
+}
+