1 files changed, 111 insertions, 0 deletions
diff --git a/browser/base/content/test/tabs/browser_overflowScroll.js b/browser/base/content/test/tabs/browser_overflowScroll.js
new file mode 100644
index 0000000000..e30311bef1
--- /dev/null
+++ b/browser/base/content/test/tabs/browser_overflowScroll.js
@@ -0,0 +1,111 @@
+"use strict";
+
+requestLongerTimeout(2);
+
+/**
+ * Tests that scrolling the tab strip via the scroll buttons scrolls the right
+ * amount in non-smoothscroll mode.
+ */
+add_task(async function () {
+  let arrowScrollbox = gBrowser.tabContainer.arrowScrollbox;
+  let scrollbox = arrowScrollbox.scrollbox;
+
+  let rect = ele => ele.getBoundingClientRect();
+  let width = ele => rect(ele).width;
+
+  let left = ele => rect(ele).left;
+  let right = ele => rect(ele).right;
+  let isLeft = (ele, msg) => is(left(ele), left(scrollbox), msg);
+  let isRight = (ele, msg) => is(right(ele), right(scrollbox), msg);
+  let elementFromPoint = x => arrowScrollbox._elementFromPoint(x);
+  let nextLeftElement = () => elementFromPoint(left(scrollbox) - 1);
+  let nextRightElement = () => elementFromPoint(right(scrollbox) + 1);
+  let firstScrollable = () => gBrowser.tabs[gBrowser._numPinnedTabs];
+  let waitForNextFrame = async function () {
+    await new Promise(requestAnimationFrame);
+    await new Promise(resolve => Services.tm.dispatchToMainThread(resolve));
+  };
+
+  await BrowserTestUtils.overflowTabs(registerCleanupFunction, window, {
+    overflowAtStart: false,
+    overflowTabFactor: 3,
+  });
+
+  gBrowser.pinTab(gBrowser.tabs[0]);
+
+  await BrowserTestUtils.waitForCondition(() => {
+    return Array.from(gBrowser.tabs).every(tab => tab._fullyOpen);
+  });
+
+  ok(
+    arrowScrollbox.hasAttribute("overflowing"),
+    "Tab strip should be overflowing"
+  );
+
+  let upButton = arrowScrollbox._scrollButtonUp;
+  let downButton = arrowScrollbox._scrollButtonDown;
+  let element;
+
+  gBrowser.selectedTab = firstScrollable();
+  await TestUtils.waitForTick();
+
+  ok(
+    left(scrollbox) <= left(firstScrollable()),
+    "Selecting the first tab scrolls it into view " +
+      "(" +
+      left(scrollbox) +
+      " <= " +
+      left(firstScrollable()) +
+      ")"
+  );
+
+  element = nextRightElement();
+  EventUtils.synthesizeMouseAtCenter(downButton, {});
+  await waitForNextFrame();
+  isRight(element, "Scrolled one tab to the right with a single click");
+
+  gBrowser.selectedTab = gBrowser.tabs[gBrowser.tabs.length - 1];
+  await waitForNextFrame();
+  ok(
+    right(gBrowser.selectedTab) <= right(scrollbox),
+    "Selecting the last tab scrolls it into view " +
+      "(" +
+      right(gBrowser.selectedTab) +
+      " <= " +
+      right(scrollbox) +
+      ")"
+  );
+
+  element = nextLeftElement();
+  EventUtils.synthesizeMouseAtCenter(upButton, {});
+  await waitForNextFrame();
+  isLeft(element, "Scrolled one tab to the left with a single click");
+
+  let elementPoint = left(scrollbox) - width(scrollbox);
+  element = elementFromPoint(elementPoint);
+  element = element.nextElementSibling;
+
+  EventUtils.synthesizeMouseAtCenter(upButton, { clickCount: 2 });
+  await waitForNextFrame();
+  await BrowserTestUtils.waitForCondition(
+    () => !gBrowser.tabContainer.arrowScrollbox._isScrolling
+  );
+  isLeft(element, "Scrolled one page of tabs with a double click");
+
+  EventUtils.synthesizeMouseAtCenter(upButton, { clickCount: 3 });
+  await waitForNextFrame();
+  var firstScrollableLeft = left(firstScrollable());
+  ok(
+    left(scrollbox) <= firstScrollableLeft,
+    "Scrolled to the start with a triple click " +
+      "(" +
+      left(scrollbox) +
+      " <= " +
+      firstScrollableLeft +
+      ")"
+  );
+
+  while (gBrowser.tabs.length > 1) {
+    BrowserTestUtils.removeTab(gBrowser.tabs[0]);
+  }
+});