css/cssom/adoptedstylesheets-observablearray.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Adoptedstylesheets as ObservableArray</title>
<link rel="author" href="mailto:masonf@chromium.org">
<link rel="help" href="https://drafts.csswg.org/cssom/#extensions-to-the-document-or-shadow-root-interface">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<span id=target>Test Span</span>
<div id="divNonConstructed" class="nonConstructed"></div>
<style>
  #target {background-color: red;}
</style>

<script>

const shadowRootNonConstructed = divNonConstructed.attachShadow({mode:'open'})
nonConstructedStyle = document.createElement("style");
shadowRootNonConstructed.appendChild(nonConstructedStyle);
nonConstructedStyle.sheet.insertRule(".nonConstructed { color: red; }", 0);
const nonConstructedStyleSheet = nonConstructedStyle.sheet;

function assert_is(targetStyle, color) {
  assert_equals(targetStyle.getPropertyValue('background-color'), color);
}

function testRoot(d, targetStyle) {
  const red = 'rgb(255, 0, 0)';
  const green = 'rgb(0, 255, 0)';
  const blue = 'rgb(0, 0, 255)';

  const sheet1 = new CSSStyleSheet();
  sheet1.replaceSync('#target {background-color:lime !important;}');
  const sheet2 = new CSSStyleSheet();
  sheet2.replaceSync('#target {background-color:blue !important;}');
  assert_equals(d.adoptedStyleSheets.length, 0);
  assert_is(targetStyle, red);

  d.adoptedStyleSheets = [sheet1];
  assert_equals(d.adoptedStyleSheets.length, 1);
  assert_is(targetStyle, green);

  d.adoptedStyleSheets.push(sheet2);
  assert_equals(d.adoptedStyleSheets.length, 2);
  assert_is(targetStyle, blue);

  d.adoptedStyleSheets.pop();
  assert_equals(d.adoptedStyleSheets.length, 1);
  assert_is(targetStyle, green);

  d.adoptedStyleSheets.push(sheet2);
  d.adoptedStyleSheets.reverse();
  assert_equals(d.adoptedStyleSheets.length, 2);
  assert_is(targetStyle, green);

  d.adoptedStyleSheets.splice(1, 1);
  assert_equals(d.adoptedStyleSheets.length, 1);
  assert_is(targetStyle, blue);
  d.adoptedStyleSheets.splice(0, 1, sheet1);
  assert_equals(d.adoptedStyleSheets.length, 1);
  assert_is(targetStyle, green);

  // Adding non-constructed stylesheet to AdoptedStyleSheets is not allowed.
  assert_throws_dom('NotAllowedError', () => { document.adoptedStyleSheets.push(nonConstructedStyleSheet); });

  assert_throws_js(TypeError, () => { document.adoptedStyleSheets.push("foo"); });
}

test(function() {
  const target = document.querySelector('#target');
  const targetStyle = window.getComputedStyle(target);
  testRoot(document, targetStyle);
}, "document.adoptedStyleSheets should allow mutation in-place");

test(function() {
  const host = document.createElement('div');
  document.body.appendChild(host);
  const shadow = host.attachShadow({mode: 'open'});
  shadow.innerHTML = '<span id=target>Test Shadow Span</span><style>#target{background-color: red;}</style>';
  const target = shadow.querySelector('#target');
  const targetStyle = window.getComputedStyle(target);
  testRoot(shadow, targetStyle);
}, "shadowRoot.adoptedStyleSheets should allow mutation in-place");

test(function() {
  assert_true(Array.isArray(document.adoptedStyleSheets));
  const host = document.createElement('div');
  document.body.appendChild(host);
  const shadow = host.attachShadow({mode: 'open'});
  assert_true(Array.isArray(shadow.adoptedStyleSheets));
}, "adoptedStyleSheets should return true for isArray()");
</script>