chromium/third_party/blink/web_tests/fast/forms/text/input-appearance-offset-size.html

<html>
<script src="../../../resources/testharness.js"></script>
<script src="../../../resources/testharnessreport.js"></script>
<body>
<p>This tests that an input field does not change its size when a value is previewed.</p>

<div><input id="emptyInput" style="font: 12px Arial"></div>
<div><input id="previewInput" style="font: 12px Arial"></div>

<div><textarea id="emptyTextArea" style="font: 12px Arial"></textarea></div>
<div><textarea id="previewTextArea" style="font: 12px Arial"></textarea></div>
<script>
test(() => {
    var empty = document.getElementById('emptyInput');
    var preview = document.getElementById('previewInput');

    internals.setSuggestedValue(preview, 'Foooooooooooooooooooooooooooooooooooo');

    assert_equals(empty.offsetWidth, preview.offsetWidth, 'Elements should have same width');
    assert_equals(empty.offsetHeight, preview.offsetHeight, 'Elements should have same height');
}, 'Testing that an <input> field does not change its size when a value is previewed.');

test(() => {
    var empty = document.getElementById('emptyTextArea');
    var preview = document.getElementById('previewTextArea');

    internals.setSuggestedValue(preview, 'Foooooooooooooooooooooooooooooooooooo');

    assert_equals(empty.offsetWidth, preview.offsetWidth, 'Elements should have same width');
    assert_equals(empty.offsetHeight, preview.offsetHeight, 'Elements should have same height');
}, 'Testing that an <textarea> field does not change its size when a value is previewed.');

</script>
</body>
</html>