chromium/src/third_party/blink/web_tests/external/wpt/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/document-open-side-effects.js

function assertDocumentIsReadyForSideEffectsTest(doc, description) {
  assert_not_equals(doc.childNodes.length, 0, `document should not be empty before side effects test (${description})`);
}

function assertOpenHasNoSideEffects(doc, originalURL, description) {
  assert_not_equals(doc.childNodes.length, 0, `document nodes should not be cleared (${description})`);
  assert_equals(doc.URL, originalURL, `The original URL should be kept (${description})`);
}