chromium/third_party/blink/web_tests/external/wpt/css/css-fonts/variations/font-weight-metrics.html

<!DOCTYPE html>
<html>
<title>CSS Fonts - Test that variable-font glyph advances depend on applied weight</title>
<link rel="author" title="Jonathan Kew" href="[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-fonts-4/#font-weight-prop"/>
<link rel="help" href="https://drafts.csswg.org/css-fonts-4/#font-prop-desc"/>
<link rel="match" href="font-weight-metrics-ref.html">
<meta name="assert" content="Ensures that glyph advances are adjusted appropriately when the weight axis is varied."/>
<meta charset="utf-8">

<style>
@font-face {
  font-family: test;
  font-weight: 100 900;
  src: url(resources/Inter.var.subset.ttf);
}
div {
  font: 32px test;
  position: absolute;
  margin: 1em;
}
.light {
  background: red;
  color: red;
  font-weight: 100;
}
.heavy {
  background: green;
  color: green;
  font-weight: 900;
}
</style>

Test passes if there is a green rectangle and <strong>no red</strong>:

<!-- Red background that should be entirely covered by the div with the heavy face -->
<div class=light>
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
</div>

<!-- The string here is two characters shorter, but the advance width of the heavy
     glyphs should be large enough that the light div is still completely covered. -->
<div class=heavy>
aaaaaaaaaaaaaaaaaaaaaaaaaaaa
</div>