test_keyboard_scroll_from_fixed_pos.html

Enable keyboard shortcuts

<!DOCTYPE HTML>

<html>

<head>

<meta charset="utf-8">

<title>Test main-thread keyboard scrolling when the focused content is fixed to the viewport</title>

<script src="/tests/SimpleTest/SimpleTest.js"></script>

<link rel="stylesheet" href="/tests/SimpleTest/test.css"/>

</head>

<body>

<!-- The mochitest test frame itself is scrolling="no", so the scrollable root

     scroll container under test has to live in a nested frame. -->

<iframe id="subframe" srcdoc="

  <div id='fixed' tabindex='0' style='position:fixed; top:0; left:0'>focus</div>

  <div style='height:3000px'></div>

"></iframe>

<pre id="test">

<script>

add_task(async function keyboard_scroll_from_fixed_pos() {

  await SpecialPowers.pushPrefEnv({set: [["general.smoothScroll", false]]});

  const subWindow = document.getElementById("subframe").contentWindow;

  const subDocument = subWindow.document;

  const fixed = subDocument.getElementById("fixed");

  ok(subDocument.scrollingElement.scrollHeight >

     subDocument.scrollingElement.clientHeight,

     "the nested root scroll container has vertical scroll range");

  fixed.focus();

  is(subDocument.activeElement, fixed, "the fixed element is focused");

  is(subWindow.scrollY, 0, "the nested frame has not scrolled yet");

  const scrollEndPromise = new Promise(resolve =>

    subWindow.addEventListener("scrollend", resolve, { once: true }));

  SpecialPowers.doCommand(subWindow, "cmd_scrollLineDown");

  await scrollEndPromise;

  ok(subWindow.scrollY > 0,

     "the root scroll container scrolled down with the fixed element focused");

});

</script>

</pre>

</body>

</html>