css/css-variables/variables-animation-math-functions.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>angle custom properties interpolation with css math functions</title>
    <link rel="author" title="Daniil Sakhapov" href="mailto:sakhapov@chromium.org">
    <link rel="help" href="https://drafts.csswg.org/css-values/#sign-funcs">
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <script src="/css/support/interpolation-testcommon.js"></script>
  </head>
  <style>
    :root {
      font-size: 10px;
    }
    @property --my-angle {
      syntax: "<angle>";
      initial-value: 0deg;
      inherits: false;
    }
  </style>
  <body>
    <script>
      test_interpolation({
        property: '--my-angle',
        from: '100deg',
        to: 'calc(sign(20rem - 20px) * 180deg)',
      }, [
        {at: -1, expect: '20deg'},
        {at: 0, expect: '100deg'},
        {at: 0.125, expect: '110deg'},
        {at: 0.875, expect: '170deg'},
        {at: 1, expect: '180deg'},
        {at: 2, expect: '260deg'}
      ]);

      test_interpolation({
        property: '--my-angle',
        from: 'calc(sign(20rem - 20px) * 100deg)',
        to: 'calc(sign(20rem - 20px) * 180deg)',
      }, [
        {at: -1, expect: '20deg'},
        {at: 0, expect: '100deg'},
        {at: 0.125, expect: '110deg'},
        {at: 0.875, expect: '170deg'},
        {at: 1, expect: '180deg'},
        {at: 2, expect: '260deg'}
      ]);
    </script>
  </body>
</html>