chromium/third_party/blink/web_tests/external/wpt/css/css-fonts/animations/multiple-elements-font-palette-animation.html

<!DOCTYPE html>
<meta charset="UTF-8">
<title>Font-palette animation of multiple elements</title>
<link rel="help" href="https://www.w3.org/TR/css-fonts-4/#propdef-font-palette">
<meta name="assert" content="Animating font-palette CSS property of multiple elements.">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  @font-face {
    font-family: "COLR-test-font";
    src: url("../resources/COLR-palettes-test-font.ttf") format("truetype");
  }
  @font-palette-values --custom {
    font-family: "COLR-test-font";
    base-palette: 3;
  }
  @keyframes anim {
    from {
      font-palette: normal;
    }
    to {
      font-palette: --custom;
    }
  }
  .demo {
    font-family: "COLR-test-font";
    font-size: 130px;
  }
  .anim {
    animation: anim 0.1s forwards;
  }
</style>

<body>
  <div class="demo">
    <div id="a" class="anim">A</div><div id="b" class="anim">A</div>
  </div>
</body>

<script>
  var afterPaletteAnimationTest1 = async_test(
    "Verify font-palette value of the first element after animation"
  );
  document.getElementById("a").addEventListener("animationend",
    afterPaletteAnimationTest1.step_func_done(function() {
        assert_equals(window.getComputedStyle(
                document.getElementById("a"))
            .getPropertyValue('font-palette'), "--custom");
    }));

  var afterPaletteAnimationTest2 = async_test(
    "Verify font-palette value of the second element after animation"
  );
  document.getElementById("b").addEventListener("animationend",
    afterPaletteAnimationTest2.step_func_done(function() {
        assert_equals(window.getComputedStyle(
                document.getElementById("b"))
            .getPropertyValue('font-palette'), "--custom");
    }));
</script>