QA Testing — Web Application Testing with cmux_browser

Test running web applications by interacting as a real user via cmux_browser, then report findings with structured evidence.

Prerequisites

• The application must be running and accessible via HTTP
• cmux_browser tool must be available
• If the app isn't running, start it first (see Setup below)

Workflow

Step 1: Setup

If the app is already running, skip to Step 2.

If the app needs to be started:

# Start in a background cmux pane
cmux_split({ direction: "down", command: "cd /path/to/project && npm run dev\n" })

# Wait for it to be ready (check the pane output)
cmux_read({ surface: "surface:N" })

# Or poll the URL
cmux_browser({ action: "open", url: "http://localhost:3000" })
cmux_browser({ action: "wait", waitCondition: "load-state", loadState: "networkidle" })

If Docker is needed:

cd /path/to/project && docker compose up -d
# Wait for healthy
timeout 60 bash -c 'until curl -sf http://localhost:3000 > /dev/null; do sleep 2; done'

Step 2: Smoke Test

Verify the app loads at all before deeper testing.

# Open the app
cmux_browser({ action: "open", url: "http://localhost:3000" })

# Wait for it to load
cmux_browser({ action: "wait", waitCondition: "load-state", loadState: "networkidle" })

# Screenshot the initial state
cmux_browser({ action: "screenshot" })

# Check for JavaScript errors
cmux_browser({ action: "errors" })

# Check console output
cmux_browser({ action: "console" })

# Get a DOM snapshot (accessibility tree)
cmux_browser({ action: "snapshot" })

If the smoke test fails (page doesn't load, crash errors), stop and report immediately.

Step 3: Functional Testing

For each acceptance criterion, follow this pattern:

# 1. Navigate to the relevant state
cmux_browser({ action: "navigate", url: "/some-page" })
cmux_browser({ action: "wait", waitCondition: "load-state", loadState: "networkidle" })

# 2. Interact as a real user
cmux_browser({ action: "click", selector: "button.submit" })
cmux_browser({ action: "fill", selector: "input[name='email']", value: "test@example.com" })
cmux_browser({ action: "press", key: "Enter" })

# 3. Verify outcomes
cmux_browser({ action: "wait", waitCondition: "text", text: "Success" })
cmux_browser({ action: "snapshot", interactive: true })  # check element states
cmux_browser({ action: "get", selector: ".result", subaction: "textContent" })
cmux_browser({ action: "is", selector: ".modal", subaction: "visible" })

# 4. Screenshot as evidence
cmux_browser({ action: "screenshot" })

# 5. Check for errors after the interaction
cmux_browser({ action: "errors" })

Tips for reliable element selection:

• Use snapshot to see the accessibility tree and find the right selectors
• Use find with role for semantic targeting: cmux_browser({ action: "find", subaction: "role", name: "Submit" })
• Use identify to see interactive elements on the page
• Prefer data-testid, aria-label, or semantic selectors over fragile CSS paths

Step 4: Edge Case Testing

Be skeptical. Agents often ship code that works for the happy path but breaks on edge cases. Actively try to break things:

Test	How	What to look for
Empty state	Clear all data, visit pages with no content	Crashes, blank screens, missing "no data" messages
Empty inputs	Submit forms with empty required fields	Missing validation, silent failures, crashes
Long text	Paste 500+ character strings into inputs	Overflow, layout breaking, truncation without indication
Special characters	Input <script>alert(1)</script>, emoji 🎉, Unicode ñ	XSS, encoding errors, display issues
Rapid clicks	Double-click submit buttons, rapidly toggle switches	Duplicate submissions, race conditions, broken state
Back button	Navigate forward through a flow, then press back	Lost state, stale data, errors
Refresh	F5 / reload mid-flow	Lost state, errors, unexpected redirects
Network errors	Disconnect WiFi / block API calls (if possible)	Missing error handling, infinite spinners, blank screens

# Example: test empty form submission
cmux_browser({ action: "click", selector: "button[type='submit']" })
cmux_browser({ action: "screenshot" })
cmux_browser({ action: "errors" })

# Example: test long text
cmux_browser({ action: "fill", selector: "input[name='title']", value: "A".repeat(500) })
cmux_browser({ action: "screenshot" })

# Example: test special characters
cmux_browser({ action: "fill", selector: "input[name='name']", value: "<script>alert('xss')</script>" })
cmux_browser({ action: "click", selector: "button[type='submit']" })
cmux_browser({ action: "screenshot" })
cmux_browser({ action: "errors" })

Step 5: Accessibility Audit

Inject axe-core and run a full accessibility audit:

# Inject axe-core library
cmux_browser({ action: "eval", value: `
  await new Promise((resolve, reject) => {
    const script = document.createElement('script');
    script.src = 'https://cdnjs.cloudflare.com/ajax/libs/axe-core/4.10.2/axe.min.js';
    script.onload = resolve;
    script.onerror = reject;
    document.head.appendChild(script);
  });
  const results = await axe.run();
  return JSON.stringify({
    violations: results.violations.map(v => ({
      id: v.id,
      impact: v.impact,
      description: v.description,
      helpUrl: v.helpUrl,
      nodes: v.nodes.length
    })),
    passes: results.passes.length,
    incomplete: results.incomplete.length,
    inapplicable: results.inapplicable.length
  }, null, 2);
` })

CDN fallback: If the CDN is unreachable (air-gapped CI, network restriction, outage), the script injection will fail. In that case, fall back to:

• npx axe-cli http://localhost:3000 --save axe-report.json (CLI-based audit)
• or skip the accessibility audit and note "A11y audit skipped — axe-core CDN unavailable" in the report

Security note: For production use, add Subresource Integrity (SRI) verification to the script tag: script.integrity = "sha384-..."; script.crossOrigin = "anonymous"; (hash available on cdnjs.com).

Interpreting axe-core results:

• critical impact — Must fix. Screen readers can't use the page.
• serious impact — Should fix. Major barrier for some users.
• moderate impact — Nice to fix. Some users affected.
• minor impact — Optional. Best practice improvements.

Scoring accessibility:

Violations	Score
0 violations	10
1-3 minor	8-9
1-3 serious	6-7
4-10 mixed	4-5
10+ or any critical	2-3

Step 6: Performance (Optional)

Run Lighthouse for performance auditing when requested:

npx lighthouse http://localhost:3000 \
  --output=json \
  --output-path=./lighthouse-report.json \
  --chrome-flags="--headless --no-sandbox" \
  --only-categories=performance,accessibility,best-practices \
  --quiet

Then read and summarize the results:

read lighthouse-report.json

Step 7: Report

Produce a structured QA report. Always include:

1. Verdict — PASS (all dimensions ≥ 6, no critical failures) or FAIL
2. Scores — 1-10 for each dimension with brief justification
3. Acceptance criteria checklist — each item explicitly PASS or FAIL
4. Bugs — with severity, reproduction steps, expected vs actual, screenshot
5. Edge cases tested — what you tried and what happened
6. Accessibility results — axe-core violation count and details
7. Screenshots — numbered, referenced in bug descriptions

Step 8: Cleanup

If you started a dev server or Docker container in Step 1, clean up:

# Stop a dev server running in a cmux pane
cmux_close({ surface: "surface:N" })

# Or stop Docker containers
cd /path/to/project && docker compose down

This prevents orphaned processes and keeps the environment clean for the next test run.

Report Template

# QA Report: [Feature/PR Name]

**Date:** YYYY-MM-DD
**App URL:** http://localhost:XXXX
**Tested by:** QA Agent

## Verdict: PASS ✅ / FAIL ❌

## Scores

| Dimension | Score | Notes |
|-----------|-------|-------|
| Functionality | X/10 | Brief justification |
| Completeness | X/10 | Brief justification |
| UX | X/10 | Brief justification |
| Robustness | X/10 | Brief justification |
| Accessibility | X/10 | N violations (N critical, N serious) |

**Average:** X.X/10

## Acceptance Criteria

- [x] Criterion 1 — PASS
- [x] Criterion 2 — PASS
- [ ] Criterion 3 — FAIL: [specific issue]

## Bugs Found

### 🔴 Bug 1: [Title] (Critical)
- **Steps:** 1. Navigate to /page 2. Click button 3. ...
- **Expected:** Form submits and shows success
- **Actual:** Page crashes with TypeError in console
- **Screenshot:** #3

### 🟡 Bug 2: [Title] (Major)
...

### 🔵 Bug 3: [Title] (Minor)
...

## Edge Cases Tested

| Test | Result | Notes |
|------|--------|-------|
| Empty form submission | ✅ PASS | Shows validation errors |
| Long text (500 chars) | ⚠️ WARN | Text overflows container |
| Special characters | ✅ PASS | Properly escaped |
| Back button | ❌ FAIL | State lost, shows blank page |
| Rapid double-click | ✅ PASS | Button disabled after first click |

## Accessibility (axe-core)

- **Violations:** N
- **Passes:** N
- **Details:**
  - [serious] button-name: 2 buttons missing accessible names
  - [moderate] color-contrast: 3 elements with insufficient contrast

## Screenshots

1. Initial load — [description]
2. After form submission — [description]
3. Bug #1 evidence — [description]

Grading Rubric Reference

Dimension	10 (Exceptional)	8-9 (Very Good)	6-7 (Good)	4-5 (Acceptable)	2-3 (Poor)
Functionality	All criteria pass, flows smooth	—	Most pass, minor issues	Some criteria fail	Core flows broken
Completeness	Everything built and working	—	Minor features missing	Significant gaps	Mostly stubs
UX	Polished, delightful	—	Good, minor rough edges	Functional but clunky	Confusing/broken
Robustness	Handles everything gracefully	—	Handles common cases	Some edge cases crash	Fragile
Accessibility	0 violations	1-3 minor violations	1-3 serious violations	4-10 mixed violations	10+ or any critical

Verdict Rules

• PASS = All dimensions ≥ 6 AND no critical functionality failures
• FAIL = Any dimension < 6 OR acceptance criteria not met

When reporting FAIL, always provide specific, actionable feedback the builder can use to fix the issues. Reference exact elements, URLs, and steps.