chromium/third_party/blink/web_tests/external/wpt/html/browsers/browsing-the-web/navigating-across-documents/navigation-unload-data-url.window.js

// META: title=data: URL navigation started from unload handler must be ignored
// META: script=../resources/helpers.js

promise_test(async () => {
  const iframe = await addIframe();

  iframe.contentWindow.addEventListener("unload", () => {
    iframe.contentWindow.location.href =
      `data:text/html,unload<script>parent.postMessage('fail', '*');</script>`;
  });

  iframe.src =
    `data:text/html,load<script>parent.postMessage('pass', '*')</script>`;
  assert_equals(await waitForMessage(iframe.contentWindow), "pass");
});