css/cssom/CSSStyleSheet-constructable-replace-cssRules.html

<!doctype html>
<meta charset="utf-8">
<title>CSSStyleSheet.replace reflects the right cssRules.</title>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<link rel="author" title="Mozilla" href="https://mozilla.org">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1864815">
<link rel="help" href="https://drafts.csswg.org/cssom/#dom-cssstylesheet-replace">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<p></p>
<script>
async function runTest(sync) {
  let sheet = new CSSStyleSheet();
  let rules = sheet.cssRules;
  function replace(text) {
    return sync ? sheet.replaceSync(text) : sheet.replace(text);
  }
  function assert_color(color) {
    assert_equals(sheet.cssRules, rules, "StyleSheet.cssRules is [SameObject]");
    assert_equals(rules.length, 1, "Should have one rule");
    assert_equals(rules[0].style.color, color, "Should be the right css rule");
  }
  async function replace_and_test(color) {
    await replace(`p { color: ${color} }`);
    assert_equals(sheet.cssRules, rules, "StyleSheet.cssRules is [SameObject]");
    assert_equals(rules.length, 1, "Should have one rule");
    assert_equals(rules[0].style.color, color, "Should be the right css rule");
  }

  await replace_and_test("red");
  await replace_and_test("green");
  document.adoptedStyleSheets.push(sheet);
  assert_equals(getComputedStyle(document.querySelector("p")).color, "rgb(0, 128, 0)", "Sheet should apply");
  document.adoptedStyleSheets.pop(sheet);
  assert_not_equals(getComputedStyle(document.querySelector("p")).color, "rgb(0, 128, 0)", "Sheet should stop applying");
}

for (let sync of [true, false]) {
  promise_test(() => runTest(sync), `cssRules tests (sync: ${sync})`);
}
</script>