automation-guardrails

Two small, framework-agnostic guardrails for Playwright and Puppeteer. No dependency on either library — both functions just need a page (or frame) object with .url() and .evaluate().

Built while running a production browser-automation tool that kept hitting the exact problems below, badly enough that it was worth extracting into something reusable.

fillEditable — reliably fill contenteditable / rich-text editors

Setting .value or .textContent on a contenteditable element is silently ignored by Draft.js, ProseMirror, CodeMirror, and similar editors. This is a well-known pain point:

• Playwright #39492 — fill() appends the new text after the existing content instead of replacing it
• Playwright #29813 — "Element is not an <input>, <textarea> or [contenteditable] element" on an element that clearly is contenteditable

fillEditable writes via document.execCommand('insertText', ...), which fires the real input events these editors listen for, then reads the field back to verify the write actually replaced the content instead of appending to it (the append case is a real, reproducible failure mode when a write races the editor's own state reconciliation — we hit it ourselves posting to a Draft.js-based editor). If verification fails, it clears the field and retries once before throwing, instead of silently submitting garbled text.

import { fillEditable } from 'automation-guardrails'

await fillEditable(page, '[data-testid="editor"]', 'Hello world')

verifyContext — confirm you're on the page you think you're on

Multi-tab automation can silently keep acting on a stale page after a navigation, a manual tab switch, or a race between two async operations. This is the browser-automation equivalent of a null check: cheap to add, expensive to debug without it.

import { verifyContext } from 'automation-guardrails'

await verifyContext(page, '/dashboard') // throws if page.url() doesn't include this
// or, to handle it yourself instead of throwing:
const result = await verifyContext(page, /\/dashboard$/, { onMismatch: 'return' })
if (!result.ok) { /* ... */ }

Install

npm install automation-guardrails

What this is not

Not a replacement for Playwright's own locator.fill() on real <input>/<textarea> elements — use that, it's fine. This is specifically for the contenteditable/rich-text case where .fill() and .type() are known to misbehave, and for the multi-tab correctness gap that neither library checks for you.

License

MIT