chromium/third_party/blink/web_tests/fast/forms/suggestion-picker/week-suggestion-picker-appearance.html

<!DOCTYPE html>
<meta name=fuzzy content="maxDifference=0-3; totalPixels=0-1000">
<script src="../../../resources/testdriver.js"></script>
<script src="../../../resources/testdriver-vendor.js"></script>
<script src="../resources/picker-common.js"></script>

<body style="background-color: #eeffff;">
<input type=week value="10000-W12" list="suggestions" style="width: 200px;">
<datalist id=suggestions>
  <option>2012-W00</option> <!--invalid-->
  <option>2012-01-01</option> <!--invalid-->
  <option>foo</option> <!--invalid-->
  <option label="This Week">2012-W01</option>
  <option>2012-W02</option>
  <option>2012-W03</option>
  <option>2012-W04</option>
  <option>2012-W05</option>
  <option>2012-W06</option>
  <option>2012-W07</option>
  <option>2012-W08</option>
  <option>2012-W09</option>
  <option>2012-W10</option>
  <option>2012-W11</option>
  <option>2012-W12</option>
  <option>2012-W13</option>
  <option>2012-W14</option>
  <option>2012-W15</option>
  <option>2012-W16</option>
  <option>2012-W17</option>
  <option>2012-W18</option>
  <option>2012-W19</option>
</datalist>

<script>
  window.onload = openPickerAppearanceOnly(document.querySelector('input'),() => {
    internals.pagePopupWindow.focus();
    eventSender.keyDown('ArrowDown');
  });
</script>