[Bug]: getByLabel (and accessible name) ignore <label> for form-associated custom elements

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関連するプルリクエストがすでにマージされています。

  • #43900 @microsoft-playwright-automation による — マージ済み

評価

難易度
3/5
見積もり時間
1〜2日
初心者へのやさしさ
25/100
issue の種類
バグ
明瞭さ
明確に書かれている
活発さ
停滞
技術スタック
html, playwright, typescript
領域
accessibility, testing-qa

調査の方向性

Start in packages/injected/src/selectorUtils.ts and read getElementLabels, then trace how those labels feed getByLabel and accessible name computation. A linked pull request (#43900) is already open; completion would require both locators in the reproduction to resolve to the custom element and the related tests to pass.

索引モデルが issue の本文から書いたものです。

説明

needs-triage
Version

1.64.1

Steps to reproduce
import { test, expect } from '@playwright/test';

test('label of a form-associated custom element', async ({ page }) => {
  await page.setContent(`
    <label for="city">City</label><my-field id="city">Pick one</my-field>
    <label>Street <my-field>Pick one</my-field></label>`);
  await page.addScriptTag({ content: `
    customElements.define('my-field', class extends HTMLElement {
      static formAssociated = true;
      constructor() { super(); this.attachInternals(); }
      connectedCallback() { this.tabIndex = 0; }
    });` });

  // The browser associates both labels with the custom elements:
  expect(await page.evaluate(() => [...document.querySelectorAll('label')].map((l) => l.control?.localName)))
    .toEqual(['my-field', 'my-field']);

  await expect(page.getByLabel('City')).toHaveCount(1);   // ❌ 0
  await expect(page.getByLabel('Street')).toHaveCount(1); // ❌ 0
});
Expected behavior

getByLabel('City') and getByLabel('Street') each resolve to the <my-field> element.

Form-associated custom elements are labelable elements. The browser associates the <label> with them, both for for= and for nesting: label.control returns the element, and Chrome's accessibility tree names it from the label (with role = 'combobox' set through ElementInternals, Chrome exposes combobox "City").

Actual behavior

Both locators resolve to 0 elements.

getElementLabels (packages/injected/src/selectorUtils.ts) reads element.labels only for a fixed list of native elements:

const isNonHiddenInput = element.nodeName === 'INPUT' && element.type !== 'hidden';
if (['BUTTON', 'METER', 'OUTPUT', 'PROGRESS', 'SELECT', 'TEXTAREA'].includes(element.nodeName) || isNonHiddenInput) {
  const labels = element.labels;
  ...

A form-associated custom element has no public .labels (only ElementInternals.labels, which is private to the element), so the element side can't be read. The label side can: HTMLLabelElement.control returns the custom element for both for= and nesting, so no new browser API is needed.

Additional context
  • Related, but different: #34264 (roles and states set through ElementInternals). That one needs access to the element's internals. This one doesn't: the association is readable today through label.control.
  • Possible fix: when the element is a form-associated custom element (customElements.get(el.localName)?.formAssociated), collect the <label> elements in its tree whose control === el, and use their text, excluding the text of the control nested inside a label (as is already done for native controls). The same labels should feed the accessible name computation (step 2D) used by getByRole({ name }).
  • It matters more and more: design systems build form controls as form-associated custom elements precisely so that <label for> works as with native controls.
Environment
Playwright 1.64.1, Chrome. The lookup happens in Playwright's injected script, so it shouldn't depend on the browser.
主要言語
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