1 files changed, 91 insertions, 0 deletions
diff --git a/browser/base/content/test/general/browser_overflowScroll.js b/browser/base/content/test/general/browser_overflowScroll.js
new file mode 100644
index 000000000..56932fae2
--- /dev/null
+++ b/browser/base/content/test/general/browser_overflowScroll.js
@@ -0,0 +1,91 @@
+var tabstrip = gBrowser.tabContainer.mTabstrip;
+var scrollbox = tabstrip._scrollbox;
+var originalSmoothScroll = tabstrip.smoothScroll;
+var tabs = gBrowser.tabs;
+
+var rect = ele => ele.getBoundingClientRect();
+var width = ele => rect(ele).width;
+var left = ele => rect(ele).left;
+var right = ele => rect(ele).right;
+var isLeft = (ele, msg) => is(left(ele) + tabstrip._tabMarginLeft, left(scrollbox), msg);
+var isRight = (ele, msg) => is(right(ele) - tabstrip._tabMarginRight, right(scrollbox), msg);
+var elementFromPoint = x => tabstrip._elementFromPoint(x);
+var nextLeftElement = () => elementFromPoint(left(scrollbox) - 1);
+var nextRightElement = () => elementFromPoint(right(scrollbox) + 1);
+var firstScrollable = () => tabs[gBrowser._numPinnedTabs];
+
+function test() {
+  requestLongerTimeout(2);
+  waitForExplicitFinish();
+
+  // If the previous (or more) test finished with cleaning up the tabs,
+  // there may be some pending animations. That can cause a failure of
+  // this tests, so, we should test this in another stack.
+  setTimeout(doTest, 0);
+}
+
+function doTest() {
+  tabstrip.smoothScroll = false;
+
+  var tabMinWidth = parseInt(getComputedStyle(gBrowser.selectedTab, null).minWidth);
+  var tabCountForOverflow = Math.ceil(width(tabstrip) / tabMinWidth * 3);
+  while (tabs.length < tabCountForOverflow)
+    gBrowser.addTab("about:blank", {skipAnimation: true});
+  gBrowser.pinTab(tabs[0]);
+
+  tabstrip.addEventListener("overflow", runOverflowTests, false);
+}
+
+function runOverflowTests(aEvent) {
+  if (aEvent.detail != 1)
+    return;
+
+  tabstrip.removeEventListener("overflow", runOverflowTests, false);
+
+  var upButton = tabstrip._scrollButtonUp;
+  var downButton = tabstrip._scrollButtonDown;
+  var element;
+
+  gBrowser.selectedTab = firstScrollable();
+  ok(left(scrollbox) <= left(firstScrollable()), "Selecting the first tab scrolls it into view " +
+     "(" + left(scrollbox) + " <= " + left(firstScrollable()) + ")");
+
+  element = nextRightElement();
+  EventUtils.synthesizeMouseAtCenter(downButton, {});
+  isRight(element, "Scrolled one tab to the right with a single click");
+
+  gBrowser.selectedTab = tabs[tabs.length - 1];
+  ok(right(gBrowser.selectedTab) <= right(scrollbox), "Selecting the last tab scrolls it into view " +
+     "(" + right(gBrowser.selectedTab) + " <= " + right(scrollbox) + ")");
+
+  element = nextLeftElement();
+  EventUtils.synthesizeMouse(upButton, 1, 1, {});
+  isLeft(element, "Scrolled one tab to the left with a single click");
+
+  let elementPoint = left(scrollbox) - width(scrollbox);
+  element = elementFromPoint(elementPoint);
+  if (elementPoint == right(element)) {
+    element = element.nextSibling;
+  }
+  EventUtils.synthesizeMouse(upButton, 1, 1, {clickCount: 2});
+  isLeft(element, "Scrolled one page of tabs with a double click");
+
+  EventUtils.synthesizeMouse(upButton, 1, 1, {clickCount: 3});
+  var firstScrollableLeft = left(firstScrollable());
+  ok(left(scrollbox) <= firstScrollableLeft, "Scrolled to the start with a triple click " +
+     "(" + left(scrollbox) + " <= " + firstScrollableLeft + ")");
+
+  for (var i = 2; i; i--)
+    EventUtils.synthesizeWheel(scrollbox, 1, 1, { deltaX: -1.0, deltaMode: WheelEvent.DOM_DELTA_LINE });
+  is(left(firstScrollable()), firstScrollableLeft, "Remained at the start with the mouse wheel");
+
+  element = nextRightElement();
+  EventUtils.synthesizeWheel(scrollbox, 1, 1, { deltaX: 1.0, deltaMode: WheelEvent.DOM_DELTA_LINE});
+  isRight(element, "Scrolled one tab to the right with the mouse wheel");
+
+  while (tabs.length > 1)
+    gBrowser.removeTab(tabs[0]);
+
+  tabstrip.smoothScroll = originalSmoothScroll;
+  finish();
+}