Browser QA — Automated Visual Testing & Interaction
When to Use
- After deploying a feature to staging/preview
- When you need to verify UI behavior across pages
- Before shipping — confirm layouts, forms, interactions actually work
- When reviewing PRs that touch frontend code
- Accessibility audits and responsive testing
How It Works
Uses the browser automation MCP (claude-in-chrome, Playwright, or Puppeteer) to interact with live pages like a real user.
Safety first — blast radius (run read-only by default)
Browser QA drives real auth and real user journeys, so treat the blast radius explicitly. Default to read-only: never run a mutating journey (checkout, payment, delete, mass-update) against a production URL — require an explicit opt-in and a staging/preview URL. Use seeded test credentials, never real production logins, and redact credentials/tokens/PII before saving any screenshot.
Phase 1: Smoke Test
1. Navigate to target URL
2. Check for console errors (filter noise: analytics, third-party)
3. Verify no 4xx/5xx in network requests
4. Screenshot above-the-fold on desktop + mobile viewport
5. Check Core Web Vitals: LCP < 2.5s, CLS < 0.1, INP < 200ms
(INP replaced FID in March 2024; thresholds per web.dev)
Phase 2: Interaction Test
1. Click every nav link — verify no dead links
2. Submit forms with valid data — verify success state
3. Submit forms with invalid data — verify error state
4. Test auth flow: login → protected page → logout (test creds only, never prod)
5. Test critical user journeys (checkout, onboarding, search)
— read-only by default; only exercise mutating journeys against staging
with explicit opt-in (see "Safety first" above)
Phase 3: Visual Regression
1. Screenshot key pages at 3 breakpoints (375px, 768px, 1440px)
2. Compare against committed baseline screenshots
— no baseline ⇒ report INCONCLUSIVE, never a silent PASS
3. Flag layout shifts > 5px, missing elements, overflow
4. Check dark mode if applicable
Phase 4: Accessibility
1. Run axe-core or equivalent on each page
2. Flag WCAG 2.2 AA violations (contrast, labels, focus order)
3. Verify keyboard navigation works end-to-end
4. Check screen reader landmarks
Note: axe-core automatically covers roughly 30–40% of WCAG. A clean run is necessary, not sufficient — keyboard nav, focus order, and a screen-reader pass still need a manual check. Don't report "accessible" from an automated pass alone.
Output Format
## QA Report — [URL] — [timestamp]
### Smoke Test
- Console errors: 0 critical, 2 warnings (analytics noise)
- Network: all 200/304, no failures
- Core Web Vitals: LCP 1.2s ✓, CLS 0.02 ✓, INP 89ms ✓
### Interactions
- [✓] Nav links: 12/12 working
- [✗] Contact form: missing error state for invalid email
- [✓] Auth flow: login/logout working
### Visual
- [✗] Hero section overflows on 375px viewport
- [✓] Dark mode: all pages consistent
### Accessibility
- 2 AA violations: missing alt text on hero image, low contrast on footer links
### Verdict: SHIP WITH FIXES (2 issues, 0 blockers)
# verdict ∈ SHIP / SHIP WITH FIXES / DO NOT SHIP; use INCONCLUSIVE if no visual baseline
Integration
Works with any browser MCP:
mChild__claude-in-chrome__*tools (preferred — uses your actual Chrome)- Playwright via
mcp__browserbase__* - Direct Puppeteer scripts
Pair with /canary-watch for post-deploy monitoring.