diff -r 000000000000 -r 6474c204b198 browser/metro/base/tests/mochitest/browser_tabs_container.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/metro/base/tests/mochitest/browser_tabs_container.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,117 @@
+// -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
+/* 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/. */
+
+"use strict";
+
+function test() {
+  runTests();
+}
+
+function setup() {
+  yield waitForCondition(function () {
+    return Elements.tabList && Elements.tabList.strip;
+  });
+
+  if (!ContextUI.tabbarVisible) {
+    ContextUI.displayTabs();
+  }
+}
+function tearDown() {
+  cleanUpOpenedTabs();
+}
+
+function isElementVisible(elm) {
+  return elm.ownerDocument.defaultView.getComputedStyle(elm).getPropertyValue("visibility") == "visible";
+}
+
+
+gTests.push({
+  desc: "No scrollbuttons when tab strip doesnt require overflow",
+  setUp: setup,
+  run: function () {
+    let tabStrip = Elements.tabList.strip;
+    let tabs = Elements.tabList.strip.querySelectorAll("documenttab");
+
+    // sanity check tab count:
+    is(tabs.length, 1, "1 tab present");
+
+    // test imprecise mode
+    let imprecisePromise = waitForObserver("metro_imprecise_input");
+    notifyImprecise();
+    yield imprecisePromise;
+
+    ok(!isElementVisible(tabStrip._scrollButtonUp), "left scrollbutton is hidden in imprecise mode");
+    ok(!isElementVisible(tabStrip._scrollButtonDown), "right scrollbutton is hidden in imprecise mode");
+
+    // test precise mode
+    let precisePromise = waitForObserver("metro_precise_input");
+    notifyPrecise();
+    yield precisePromise;
+
+    ok(!isElementVisible(tabStrip._scrollButtonUp), "Bug 952297 - left scrollbutton is hidden in precise mode");
+    ok(!isElementVisible(tabStrip._scrollButtonDown), "right scrollbutton is hidden in precise mode");
+  },
+  tearDown: tearDown
+});
+
+gTests.push({
+  desc: "Scrollbuttons not visible when tabstrip has overflow in imprecise input mode",
+  setUp: function(){
+    yield setup();
+    // ensure we're in imprecise mode
+    let imprecisePromise = waitForObserver("metro_imprecise_input");
+    notifyImprecise();
+    yield imprecisePromise;
+  },
+  run: function () {
+    // add enough tabs to get overflow in the tabstrip
+    let strip = Elements.tabList.strip;
+    ok(strip && strip.scrollClientSize && strip.scrollSize, "Sanity check tabstrip strip is present and expected properties available");
+
+    while (strip.scrollSize <= strip.scrollClientSize) {
+      yield addTab("about:mozilla");
+    }
+
+    ok(!isElementVisible(Elements.tabList.strip._scrollButtonUp), "left scrollbutton is hidden in imprecise mode");
+    ok(!isElementVisible(Elements.tabList.strip._scrollButtonDown), "right scrollbutton is hidden in imprecise mode");
+
+  }
+});
+
+gTests.push({
+  desc: "Scrollbuttons become visible when tabstrip has overflow in precise input mode",
+  setUp: function(){
+    yield setup();
+    // ensure we're in precise mode
+    let precisePromise = waitForObserver("metro_precise_input");
+    notifyPrecise();
+    yield precisePromise;
+  },
+  run: function () {
+    let strip = Elements.tabList.strip;
+    ok(strip && strip.scrollClientSize && strip.scrollSize, "Sanity check tabstrip is present and expected properties available");
+
+    // add enough tabs to get overflow in the tabstrip
+    while (strip.scrollSize <= strip.scrollClientSize) {
+      yield addTab("about:mozilla");
+    }
+
+    ok(isElementVisible(Elements.tabList.strip._scrollButtonUp), "left scrollbutton should be visible in precise mode");
+    ok(isElementVisible(Elements.tabList.strip._scrollButtonDown), "right scrollbutton should be visible in precise mode");
+
+    // select the first tab
+    Browser.selectedTab = Browser.tabs[0];
+    yield waitForMs(1000); // XXX maximum duration of arrowscrollbox _scrollAnim
+    ok(Elements.tabList.strip._scrollButtonUp.disabled, "left scrollbutton should be disabled when 1st tab is selected and tablist has overflow");
+    ok(!Elements.tabList.strip._scrollButtonDown.disabled, "right scrollbutton should be enabled when 1st tab is selected and tablist has overflow");
+
+    // select the last tab
+    Browser.selectedTab = Browser.tabs[Browser.tabs.length - 1];
+    yield waitForMs(1000); // XXX maximum duration of arrowscrollbox _scrollAnim
+    ok(!Elements.tabList.strip._scrollButtonUp.disabled, "left scrollbutton should be enabled when 1st tab is selected and tablist has overflow");
+    ok(Elements.tabList.strip._scrollButtonDown.disabled, "right scrollbutton should be disabled when last tab is selected and tablist has overflow");
+
+  }
+});