feat: fillField works with role=combobox widgets

[DavertMik]

Problem

I.fillField('Country', 'Ukr') does not work against comboboxes whose trigger is not a text field — the shadcn / Base UI pattern where a <button role="combobox"> opens a popup containing the search input.

Worse, against Base UI it silently passes while doing nothing. Base UI renders:

<label for="value-input" id="country-label">Country</label>
<button role="combobox" aria-labelledby="country-label"></button>
<input id="value-input" name="content" tabindex="-1" aria-hidden="true" style="clip:rect(0,0,0,0);position:fixed">

The <label for> points at the aria-hidden form-value proxy, not at the trigger. Locator.field.labelEquals is tried first in findFields and matches that proxy, so fillField types into a zero-size invisible input and the step resolves green while the app never sees the interaction.

What changed

Locator.field skips aria-hidden proxies (lib/locator.js) — one predicate added to the input | textarea | select branches of all four builders, so all three helpers are fixed in one place. With the proxy filtered, resolution falls through to labelContains → aria-labelledby → the trigger.

fillField handles combobox triggers (lib/helper/extras/comboBox.js) — a <button role="combobox">, a <div role="combobox">, or a readonly input trigger is expanded, its search input located, and the value typed there. The popup is left open and filtered so an option can be picked:

I.fillField('Country', 'Ukr')
I.click('Ukraine')

Locating the input walks, in order: an editable descendant of the trigger (ARIA 1.1 wrapper, no click needed), the aria-controls/aria-owns container, a visible [role=dialog]/[role=listbox] popup, then the focused element. Two details are measured rather than assumed:

• Focus lands asynchronously ~80ms after click() resolves in Base UI (pointerdown t=0 → click t=3 → focusin t=82), so the search is polled to a 1s deadline instead of sampled once.
• The element focused before the click is excluded, so a previously focused field never receives the keystrokes.

A combobox exposing no text input raises combobox exposes no text input to type into. Use I.selectOption() to pick one of its options. rather than typing into nothing.

role="combobox" inputs (Base UI inline, MUI, Downshift) also route through this path, so they are typed with real keystrokes rather than a one-shot fill() — comboboxes that filter on keydown need that.

Detection reuses the single evaluate that richTextEditor already runs per fillField, so no extra round-trip is added to ordinary fills.

Tests

New belt in test/helper/webapi.js, so it runs against Playwright, Puppeteer and WebDriver — mirroring the rich-editor belt. Fixtures load Base UI 1.0.0-rc.0 from CDN with no build step (test/data/app/view/form/combobox/), covering the button trigger, the inline input, and custom_select.php as the negative case.

Each variant asserts: typing filters the options, the picked option submits, a pre-populated value is rewritten, and keystrokes do not leak to an outer focused input. Locator.field gets unit tests in test/unit/locator_test.js.

Local: 9/9 combobox belt on Playwright and Puppeteer, 75/75 fillField on Playwright (rich editors included, no regressions), 15/15 selectOption, 772 unit tests. WebDriver has no local server here — relying on CI.

Note for review: test/data/app/view/form/combobox/* pull React and Base UI from esm.sh, a CDN this repo has not used before (existing fixtures use jsdelivr). Versions are pinned exactly.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Ut1rjeUiZmKU7V61CeYhns

[DavertMik]

Absoltely terrible code