chromium/src/third_party/blink/web_tests/fast/spatial-navigation/snav-radio.html

<table style="text-align: left; width: 100%; margin-left: auto; margin-right: auto;" border="1" cellpadding="2" cellspacing="1">
  <tbody>
    <tr>
      <td style="vertical-align: top; text-align: center;"></td>
      <td style="vertical-align: top; text-align: center;"><a id="2" href="a">2</a></td>
      <td style="vertical-align: top; text-align: center;"></td>
    </tr>
    <tr>
      <td style="vertical-align: top; text-align: center;"><a id="4" href="a">4</a></td>
      <td style="vertical-align: top; text-align: center;"><input type="radio" id="start" ></td>
      <td style="vertical-align: top; text-align: center;"><a id="6" href="a">6</a></td>
    </tr>
    <tr>
      <td style="vertical-align: top; text-align: center;"></td>
      <td style="vertical-align: top; text-align: center;"><a id="8" href="a">8</a></td>
      <td style="vertical-align: top; text-align: center;"></td>
    </tr>
  </tbody>
</table>

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="resources/snav-testharness.js"></script>
<script>
  var resultMap = [
    ["Down", "8"],
    ["Up", "start"],
    ["Up", "2"],
    ["Down", "start"],
    ["Right", "6"],
    ["Left", "start"],
    ["Left", "4"],
    ["Right", "start"],
  ];

  // Start at a known place.
  document.getElementById("start").focus();
  snav.assertFocusMoves(resultMap);
</script>