chromium/third_party/blink/web_tests/external/wpt/custom-elements/form-associated/label-delegatesFocus.html

<!DOCTYPE html>
<link rel=author href="mailto:[email protected]">
<link rel=help href="https://bugs.chromium.org/p/chromium/issues/detail?id=1300587">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>

<form>
  <label for=custom>label</label>
  <my-custom-element id=custom></my-custom-element>
</form>

<form>
  <label for=custom2><span>label</span></label>
  <my-custom-element id=custom2></my-custom-element>
</form>

<script>
class MyCustomElement extends HTMLElement {
  static formAssociated = true;
  constructor() {
    super();
    const root = this.attachShadow({
      delegatesFocus: true,
      mode: 'open'
    });
    root.appendChild(document.createElement('input'));
  }
};
customElements.define('my-custom-element', MyCustomElement);

window.onload = () => {
  promise_test(async () => {
    const label = document.querySelector('label');
    const customElement = document.getElementById('custom');
    const input = customElement.shadowRoot.querySelector('input');
    let focused = false;
    input.addEventListener("focus", evt => { focused = true; }, {once: true});
    await test_driver.click(label);
    assert_true(focused, "should have received focus");
    assert_equals(document.activeElement, customElement);
    assert_equals(customElement.shadowRoot.activeElement, input);
  }, `Clicking on a label for a form associated custom element with delegatesFocus should focus the custom element's focus delegate.`);
  promise_test(async () => {
    const span = document.querySelector('span');
    const customElement = document.getElementById('custom2');
    const input = customElement.shadowRoot.querySelector('input');
    let focused = false;
    input.addEventListener("focus", evt => { focused = true; }, {once: true});
    await test_driver.click(span);
    assert_true(focused, "should have received focus");
    assert_equals(document.activeElement, customElement);
    assert_equals(customElement.shadowRoot.activeElement, input);
  }, `Clicking on a span in a label for a form associated custom element with delegatesFocus should focus the custom element's focus delegate.`);
};
</script>