chromium/third_party/blink/web_tests/external/wpt/css/css-writing-modes/forms/select-appearance-native-computed-style.html

<!doctype html>
<link rel="author" title="Aditya Keerthi" href="https://github.com/pxlcoder">
<link rel="help" href="https://html.spec.whatwg.org/#the-select-element">
<link rel="help" href="https://drafts.csswg.org/css-writing-modes/#block-flow">
<title>Select appearance native writing mode computed style</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<select style="writing-mode: horizontal-tb">
    <option>Option 1</option>
    <option>Option 2</option>
    <option>Option 3</option>
    <option>Option 4</option>
    <option>Option 5</option>
</select>

<select style="writing-mode: vertical-lr">
    <option>Option 1</option>
    <option>Option 2</option>
    <option>Option 3</option>
    <option>Option 4</option>
    <option>Option 5</option>
</select>

<select style="writing-mode: vertical-rl">
    <option>Option 1</option>
    <option>Option 2</option>
    <option>Option 3</option>
    <option>Option 4</option>
    <option>Option 5</option>
</select>

<script>
test(() => {
  const select = document.querySelector(`select[style="writing-mode: horizontal-tb"]`);
  const style = getComputedStyle(select);
  const blockSize = parseInt(style.blockSize, 10);
  const inlineSize = parseInt(style.inlineSize, 10);
  assert_not_equals(blockSize, 0);
  assert_not_equals(inlineSize, 0);
  assert_greater_than(inlineSize, blockSize);
  assert_equals(style.blockSize, style.height);
  assert_equals(style.inlineSize, style.width);
}, `select[style="writing-mode: horizontal-tb"] block size should match height and inline size should match width`);

for (const writingMode of ["vertical-lr", "vertical-rl"]) {
  test(() => {
    const select = document.querySelector(`select[style="writing-mode: ${writingMode}"]`);
    const style = getComputedStyle(select);
    const blockSize = parseInt(style.blockSize, 10);
    const inlineSize = parseInt(style.inlineSize, 10);
    assert_not_equals(blockSize, 0);
    assert_not_equals(inlineSize, 0);
    assert_greater_than(inlineSize, blockSize);
    assert_equals(style.blockSize, style.width);
    assert_equals(style.inlineSize, style.height);
  }, `select[style="writing-mode: ${writingMode}"] block size should match width and inline size should match height`);
};
</script>