chromium/third_party/blink/web_tests/external/wpt/html/semantics/interactive-elements/the-dialog-element/focus-previous-iframe.tentative.html

<!DOCTYPE html>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<title>Test focus is moved to the previously focused element when dialog is closed</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="/resources/testdriver-vendor.js"></script>

<body>
<dialog>Dialog in parent</dialog>

<iframe srcdoc="<input><dialog> Dialog in child </dialog>"></iframe>

<input>
<script>
test(() => {
  window.onload = function() {
    const iframe = document.querySelector("iframe");
    const input = iframe.contentDocument.querySelector("input");
    // <input> in the child document is focused
    input.focus();

    const dialog = document.querySelector("dialog");
    // <dialog> in the parent document is opened
    dialog.showModal();
    dialog.close();

    assert_equals(document.activeElement, iframe);
    assert_equals(iframe.contentDocument.activeElement, input);
  }
}, "Focus should move back from parent document to child document");

test(() => {
  window.onload = function() {
    const iframe = document.querySelector("iframe");
    const input = document.querySelector("input");
    // <input> in the parent document is focused
    input.focus();

    const dialog = iframe.contentDocument.querySelector("dialog");

    // <dialog> in the child document is focused
    dialog.showModal();
    dialog.close();

    assert_equals(document.activeElement, input);
  }
}, "Focus should move back from child document to parent document");
</script>
</body>