css/css-values/if-invalidation.html

<!DOCTYPE html>
<title>CSS Values and Units Test: if() invalidation</title>
<meta name="assert" content="Test if() invalidation">
<link rel="help" href="https://drafts.csswg.org/css-values-5/#if-notation">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  html {
    --x: 3;
  }
  #test {
    --prop: if(style(--x: 3): true_value; else: false_value;);
  }
</style>

<html>
  <body>
    <div id="test"></div>
  </body>
</html>

<script>
  setup({ single_test: true });
  let elem = document.getElementById('test');
  let old_value = window.getComputedStyle(elem).getPropertyValue('--prop');
  assert_equals(old_value, "true_value");

  document.documentElement.style.setProperty('--x', '0');
  let new_value = window.getComputedStyle(elem).getPropertyValue('--prop');
  assert_equals( new_value, "false_value");
  assert_not_equals(new_value, old_value);
  done();
</script>