chromium/third_party/blink/web_tests/fast/spatial-navigation/snav-focus-rect-contains-links.html

<!doctype html>
<a id="outerA" href="www" style="margin-left: 150px">outerA</a>
<div id="containerA" style="width: 300px; height: 300px; background: pink; position: relative; margin: 20px" tabindex="0">
  <div id="containerB" style="width: 270px; height: 270px; background: yellow; position: relative; top: 15px; left: 15px" tabindex="0">
    <!-- The focusables' DOM order is not the same as their layout order.
         SpatNav should prioritize layout order. -->
    <a id="innerB" href="www" style="position: absolute; top: 150px; left: 20px">innerB</a>
    <a id="innerC" href="www" style="position: absolute; top: 150px; left: 170px">innerC</a>
    <a id="innerD" href="www" style="position: absolute; top: 230px; left: 130px">innerD</a>
    <a id="innerA" href="www" style="position: absolute; top: 20px; left: 130px">innerA</a>
  </div>
</div>
<a id="outerB" href="www" style="margin-left: 150px">outerB</a>

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="resources/snav-testharness.js"></script>
<script>
  var resultMap = [
    ["Down", "outerA"],
    ["Down", "containerA"],
    ["Down", "containerB"],
    ["Down", "innerA"],
    ["Down", "innerC"],
    ["Down", "innerD"],
    ["Down", "outerB"],
    ["Up", "containerA"],
    ["Up", "containerB"],
    ["Up", "innerD"],
    ["Up", "innerC"],
    ["Up", "innerA"],
    ["Up", "outerA"],
  ];
  snav.assertFocusMoves(resultMap);
</script>

<p><em>Manual test instruction: Ensure that all links are reachable. Especially, when the
yellow "container" is focused, ensure that its "inner" focusables can be reached.</em></p>

<p>Once the bottommost inner node gets focus, we exit the complete stack of
containers at once (moving to #outerB from #innerD). Note that we don't go back to
one of the containers because that would create focus traps.</p>

<p>Also, when holding one of the four directional keys, ensure that the page is fully scrolled
in that direction. Especially, ensure that focus does not get stuck inside the container.</p>