firefox/testing/web-platform/tests/css/cssom/CSSConditionRule-conditionText.html

<!doctype html>
<title>CSSConditionRule.conditionText</title>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-conditional-3/#cssconditionrule">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
@media not all {
  :root { color: lime }
}
</style>
<script>
test(function(t) {
  let rule = document.styleSheets[0].cssRules[0];
  assert_true(rule instanceof CSSConditionRule);
  assert_equals(rule.conditionText, "not all");
  rule.conditionText = 1;
  assert_equals(rule.conditionText, "not all");
  rule.conditionText = "all";
  assert_equals(rule.conditionText, "not all");
  assert_not_equals(getComputedStyle(document.documentElement).color, "rgb(0, 255, 0)");
});
</script>