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()");

test(function() {
  let backing = null;
  Object.defineProperty(Array.prototype, "1", {
    configurable: true,
    set(v) { backing = this; }
  });
  document.adoptedStyleSheets = [new CSSStyleSheet(), new CSSStyleSheet()];
  delete Array.prototype["1"];
  assert_equals(backing, null);
}, "adoptedStyleSheets should not expose its backing object via prototype");

test(function() {
  // A prototype-less descriptor keeps Object.defineProperty() below working
  // once Object.prototype.get is a number.
  const numeric = Object.create(null);
  numeric.value = 1;
  numeric.writable = true;
  numeric.configurable = true;
  const descriptor = new Proxy(Object.create(null), {
    has(target, key) {
      if (key === "set") {
        // Runs while the descriptor is being converted, after the initial
        // conversion has already looked up "get".
        Object.defineProperty(Object.prototype, "get", numeric);
        Object.defineProperty(Object.prototype, "set", numeric);
      }
      return false;
    },
  });
  try {
    assert_throws_js(TypeError, () => {
      Reflect.defineProperty(document.adoptedStyleSheets, "reentrantAccessor",
                             descriptor);
    });
  } finally {
    delete Object.prototype.get;
    delete Object.prototype.set;
  }
  assert_equals(
      Object.getOwnPropertyDescriptor(document.adoptedStyleSheets,
                                      "reentrantAccessor"),
      undefined);
}, "adoptedStyleSheets defineProperty should reject accessors that become non-callable during descriptor conversion");
</script>