diff -r 000000000000 -r 6474c204b198 browser/base/content/test/general/browser_ctrlTab.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/general/browser_ctrlTab.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,151 @@
+function test() {
+  gPrefService.setBoolPref("browser.ctrlTab.previews", true);
+
+  gBrowser.addTab();
+  gBrowser.addTab();
+  gBrowser.addTab();
+
+  checkTabs(4);
+
+  ctrlTabTest([2]      , 1, 0);
+  ctrlTabTest([2, 3, 1], 2, 2);
+  ctrlTabTest([]       , 4, 2);
+
+  {
+    let selectedIndex = gBrowser.tabContainer.selectedIndex;
+    pressCtrlTab();
+    pressCtrlTab(true);
+    releaseCtrl();
+    is(gBrowser.tabContainer.selectedIndex, selectedIndex,
+       "Ctrl+Tab -> Ctrl+Shift+Tab keeps the selected tab");
+  }
+
+  { // test for bug 445369
+    let tabs = gBrowser.tabs.length;
+    pressCtrlTab();
+    EventUtils.synthesizeKey("w", { ctrlKey: true });
+    is(gBrowser.tabs.length, tabs - 1, "Ctrl+Tab -> Ctrl+W removes one tab");
+    releaseCtrl();
+  }
+
+  { // test for bug 667314
+    let tabs = gBrowser.tabs.length;
+    pressCtrlTab();
+    pressCtrlTab(true);
+    EventUtils.synthesizeKey("w", { ctrlKey: true });
+    is(gBrowser.tabs.length, tabs - 1, "Ctrl+Tab -> Ctrl+W removes the selected tab");
+    releaseCtrl();
+  }
+
+  gBrowser.addTab();
+  checkTabs(3);
+  ctrlTabTest([2, 1, 0], 7, 1);
+
+  gBrowser.addTab();
+  checkTabs(4);
+
+  { // test for bug 445369
+    selectTabs([1, 2, 0]);
+
+    let selectedTab = gBrowser.selectedTab;
+    let tabToRemove = gBrowser.tabs[1];
+
+    pressCtrlTab();
+    pressCtrlTab();
+    EventUtils.synthesizeKey("w", { ctrlKey: true });
+    ok(!tabToRemove.parentNode,
+       "Ctrl+Tab*2 -> Ctrl+W removes the second most recently selected tab");
+
+    pressCtrlTab(true);
+    pressCtrlTab(true);
+    releaseCtrl();
+    ok(selectedTab.selected,
+       "Ctrl+Tab*2 -> Ctrl+W -> Ctrl+Shift+Tab*2 keeps the selected tab");
+  }
+  gBrowser.removeTab(gBrowser.tabContainer.lastChild);
+  checkTabs(2);
+
+  ctrlTabTest([1], 1, 0);
+
+  gBrowser.removeTab(gBrowser.tabContainer.lastChild);
+  checkTabs(1);
+
+  { // test for bug 445768
+    let focusedWindow = document.commandDispatcher.focusedWindow;
+    let eventConsumed = true;
+    let detectKeyEvent = function (event) {
+      eventConsumed = event.defaultPrevented;
+    };
+    document.addEventListener("keypress", detectKeyEvent, false);
+    pressCtrlTab();
+    document.removeEventListener("keypress", detectKeyEvent, false);
+    ok(eventConsumed, "Ctrl+Tab consumed by the tabbed browser if one tab is open");
+    is(focusedWindow, document.commandDispatcher.focusedWindow,
+       "Ctrl+Tab doesn't change focus if one tab is open");
+  }
+
+  // cleanup
+  if (gPrefService.prefHasUserValue("browser.ctrlTab.previews"))
+    gPrefService.clearUserPref("browser.ctrlTab.previews");
+
+  /* private utility functions */
+
+  function pressCtrlTab(aShiftKey)
+    EventUtils.synthesizeKey("VK_TAB", { ctrlKey: true, shiftKey: !!aShiftKey });
+
+  function releaseCtrl()
+    EventUtils.synthesizeKey("VK_CONTROL", { type: "keyup" });
+
+  function isOpen()
+    ctrlTab.isOpen;
+
+  function checkTabs(aTabs) {
+    var tabs = gBrowser.tabs.length;
+    if (tabs != aTabs) {
+      while (gBrowser.tabs.length > 1)
+        gBrowser.removeCurrentTab();
+      throw "expected " + aTabs + " open tabs, got " + tabs;
+    }
+  }
+
+  function selectTabs(tabs) {
+    tabs.forEach(function (index) {
+      gBrowser.selectedTab = gBrowser.tabs[index];
+    });
+  }
+
+  function ctrlTabTest(tabsToSelect, tabTimes, expectedIndex) {
+    selectTabs(tabsToSelect);
+
+    var indexStart = gBrowser.tabContainer.selectedIndex;
+    var tabCount = gBrowser.tabs.length;
+    var normalized = tabTimes % tabCount;
+    var where = normalized == 1 ? "back to the previously selected tab" :
+                normalized + " tabs back in most-recently-selected order";
+
+    for (let i = 0; i < tabTimes; i++) {
+      pressCtrlTab();
+
+      if (tabCount > 2)
+       is(gBrowser.tabContainer.selectedIndex, indexStart,
+         "Selected tab doesn't change while tabbing");
+    }
+
+    if (tabCount > 2) {
+      ok(isOpen(),
+         "With " + tabCount + " tabs open, Ctrl+Tab opens the preview panel");
+
+      releaseCtrl();
+
+      ok(!isOpen(),
+         "Releasing Ctrl closes the preview panel");
+    } else {
+      ok(!isOpen(),
+         "With " + tabCount + " tabs open, Ctrl+Tab doesn't open the preview panel");
+    }
+
+    is(gBrowser.tabContainer.selectedIndex, expectedIndex,
+       "With "+ tabCount +" tabs open and tab " + indexStart
+       + " selected, Ctrl+Tab*" + tabTimes + " goes " + where);
+  }
+}