diff -r 000000000000 -r 6474c204b198 browser/base/content/test/general/browser_bug580956.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/general/browser_bug580956.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,27 @@
+function numClosedTabs()
+  SessionStore.getClosedTabCount(window);
+
+function isUndoCloseEnabled() {
+  updateTabContextMenu();
+  return !document.getElementById("context_undoCloseTab").disabled;
+}
+
+function test() {
+  waitForExplicitFinish();
+
+  gPrefService.setIntPref("browser.sessionstore.max_tabs_undo", 0);
+  gPrefService.clearUserPref("browser.sessionstore.max_tabs_undo");
+  is(numClosedTabs(), 0, "There should be 0 closed tabs.");
+  ok(!isUndoCloseEnabled(), "Undo Close Tab should be disabled.");
+
+  var tab = gBrowser.addTab("http://mochi.test:8888/");
+  var browser = gBrowser.getBrowserForTab(tab);
+  browser.addEventListener("load", function() {
+    browser.removeEventListener("load", arguments.callee, true);
+
+    gBrowser.removeTab(tab);
+    ok(isUndoCloseEnabled(), "Undo Close Tab should be enabled.");
+
+    finish();
+  }, true);
+}