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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /custom-elements/perform-microtask-checkpoint-before-construction.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<html>
<head>
<title>Custom Elements: create an element for a token must perform a microtask checkpoint</title>
<meta name="author" title="Ryosuke Niwa" href="mailto:rniwa@webkit.org">
<meta name="assert" content="When the HTML parser creates an element for a token, it must perform a microtask checkpoint before invoking the constructor">
<meta name="help" content="https://html.spec.whatwg.org/multipage/parsing.html#create-an-element-for-the-token">
<meta name="help" content="https://html.spec.whatwg.org/multipage/webappapis.html#perform-a-microtask-checkpoint">
<meta name="help" content="https://html.spec.whatwg.org/multipage/parsing.html#adoption-agency-algorithm">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/custom-elements-helpers.js"></script>
</head>
<body>
<div id="log"></div>
<script>
async function construct_custom_element_in_parser(test, markup)
{
const window = await create_window_in_test(test, `
<!DOCTYPE html>
<html>
<body><script>
class SomeElement extends HTMLElement {
constructor() {
super();
window.recordsListInConstructor = recordsList.map((records) => records.slice(0));
}
}
customElements.define('some-element', SomeElement);
const recordsList = [];
const observer = new MutationObserver((records) => {
recordsList.push(records);
});
observer.observe(document.body, {childList: true, subtree: true});
window.onload = () => {
window.recordsListInDOMContentLoaded = recordsList.map((records) => records.slice(0));
}
</scr` + `ipt>${markup}</body></html>`);
return window;
}
function flatten_records_list(recordsList)
{
// MutationObserver callback batching is not deterministic across runs.
// Flatten callback batches so assertions focus on mutation semantics.
assert_true(Array.isArray(recordsList));
const flattened = [];
for (const records of recordsList) {
assert_true(Array.isArray(records));
flattened.push(...records);
}
return flattened;
}
promise_test(async function () {
const contentWindow = await construct_custom_element_in_parser(this, '<b><some-element></b>');
const contentDocument = contentWindow.document;
const constructorRecords =
flatten_records_list(contentWindow.recordsListInConstructor);
const script = contentDocument.querySelector('script');
const bElement = contentDocument.querySelector('b');
const someElement = contentDocument.querySelector('some-element');
const isBInsertionRecord = (candidate) =>
candidate.type === 'childList' &&
candidate.target === contentDocument.body &&
candidate.previousSibling === script &&
candidate.nextSibling === null &&
candidate.removedNodes.length === 0 &&
candidate.addedNodes.length === 1 &&
candidate.addedNodes[0] === bElement;
const isSomeElementInsertionRecord = (candidate) =>
candidate.type === 'childList' &&
candidate.target === bElement &&
candidate.previousSibling === null &&
candidate.nextSibling === null &&
candidate.removedNodes.length === 0 &&
candidate.addedNodes.length === 1 &&
candidate.addedNodes[0] === someElement;
assert_equals(constructorRecords.length, 1);
assert_true(isBInsertionRecord(constructorRecords[0]),
'first mutation record must be the <b> insertion into document.body');
const allRecords =
flatten_records_list(contentWindow.recordsListInDOMContentLoaded);
assert_equals(allRecords.length, 2);
assert_true(isSomeElementInsertionRecord(allRecords[1]),
'second mutation record must be the <some-element> insertion into <b>');
}, 'HTML parser must perform a microtask checkpoint before constructing a custom element');
promise_test(async function () {
const contentWindow = await construct_custom_element_in_parser(this, '<b><i>hello</b><some-element>');
const contentDocument = contentWindow.document;
const constructorRecords = flatten_records_list(contentWindow.recordsListInConstructor);
assert_equals(constructorRecords.length, 4);
let record = constructorRecords[0];
assert_equals(record.type, 'childList');
assert_equals(record.target, contentDocument.body);
assert_equals(record.previousSibling, contentDocument.querySelector('script'));
assert_equals(record.nextSibling, null);
assert_equals(record.removedNodes.length, 0);
assert_equals(record.addedNodes.length, 1);
assert_equals(record.addedNodes[0], contentDocument.querySelector('b'));
record = constructorRecords[1];
assert_equals(record.type, 'childList');
assert_equals(record.target, contentDocument.querySelector('b'));
assert_equals(record.previousSibling, null);
assert_equals(record.nextSibling, null);
assert_equals(record.removedNodes.length, 0);
assert_equals(record.addedNodes.length, 1);
assert_equals(record.addedNodes[0], contentDocument.querySelector('i'));
record = constructorRecords[2];
assert_equals(record.type, 'childList');
assert_equals(record.target, contentDocument.querySelector('i'));
assert_equals(record.previousSibling, null);
assert_equals(record.nextSibling, null);
assert_equals(record.removedNodes.length, 0);
assert_equals(record.addedNodes.length, 1);
assert_equals(record.addedNodes[0].nodeType, Node.TEXT_NODE);
assert_equals(record.addedNodes[0].data, "hello");
const secondI = contentDocument.querySelectorAll('i')[1];
record = constructorRecords[3];
assert_equals(record.type, 'childList');
assert_equals(record.target, contentDocument.body);
assert_equals(record.previousSibling, contentDocument.querySelector('b'));
assert_equals(record.nextSibling, null);
assert_equals(record.removedNodes.length, 0);
assert_equals(record.addedNodes.length, 1);
assert_equals(record.addedNodes[0], secondI);
const allRecords = flatten_records_list(contentWindow.recordsListInDOMContentLoaded);
assert_equals(allRecords.length, 5);
const someElement = contentDocument.querySelector('some-element');
const isSomeElementInsertionRecord = (candidate) =>
candidate.type === 'childList' &&
candidate.target === secondI &&
candidate.previousSibling === null &&
candidate.nextSibling === null &&
candidate.removedNodes.length === 0 &&
candidate.addedNodes.length === 1 &&
candidate.addedNodes[0] === someElement;
assert_true(isSomeElementInsertionRecord(allRecords[4]),
'last mutation record must be the <some-element> insertion into the second <i>');
}, 'HTML parser must perform a microtask checkpoint before constructing a custom element during the adoption agency algorithm');
</script>
</body>
</html>