css/css-env/env-in-custom-properties.tentative.html

<!DOCTYPE html>
<html>
  <head>
    <link rel="help" href="https://drafts.csswg.org/css-env-1/">
    <title>Test env() will work in custom properties</title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <style>
      #parent {
        --var1: inherited;
      }
      #child {
        --my-width: env(test, 100px);
        width: var(--my-width);
        --var1: env(nonexistent);
      }
    </style>
  </head>
  <body>
    <div id="parent">
      <div id="child"></div>
    </div>
    <script>
    test(() => {
      const style = window.getComputedStyle(child);
      assert_equals(style.getPropertyValue("width"), "100px");
    }, 'env() is substituted into a custom property');

    test(() => {
      const style = window.getComputedStyle(child);
      assert_equals(style.getPropertyValue("--var1"), "");
    }, 'Substitution of unrecognized env() causes guaranteed-invalid');
    </script>
  </body>
</html>