frontend-verification-testing

name	Frontend Verification & Testing
description	Verify and test Angular 18 frontend changes using Chrome DevTools MCP. Automatically check console errors, network requests, and visual rendering after implementing tasks or when fixing UI bugs. Use when creating components, debugging visual issues, validating API integration, or ensuring UI requirements are met. File types: .ts, .html, .css, .scss

Frontend Verification & Testing

Verify Angular 18 frontend using Chrome DevTools MCP - check console, network, and visual rendering.

Project Context

Photo Map MVP - Angular 18 SPA with geolocation photo management.

Stack:

• Angular 18.2.0+ (standalone components)
• Dev Server: http://localhost:4200
• Backend API: http://localhost:8080 (Spring Boot 3)
• Build: Angular CLI + esbuild

Constraints:

• Both frontend and backend must be running
• JWT authentication for protected routes
• All API calls include Authorization: Bearer <token>

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When to Use This Skill

Automatic Triggers:

1. After implementing task logic - po ukończeniu implementacji feature

   • Example: Po dodaniu Gallery Component → verify photos load
   • Example: Po implementacji Login → check form + API call

2. When uncertain about code behavior - gdy wątpliwości czy działa

   • Example: Complex RxJS pipeline → verify console
   • Example: Leaflet map init → check visual rendering

3. When fixing UI bugs (iterative) - przy naprawie błędów (sprawdź → napraw → sprawdź)

   • Example: Layout issue → screenshot → fix CSS → verify
   • Example: API 401 → check network → fix auth → verify

4. On explicit request - na żądanie użytkownika

   • Example: "zweryfikuj frontend", "sprawdź czy login działa"

DO NOT use for:

• ❌ Simple code reading (use Read tool)
• ❌ Unit test execution (use Bash with ng test)
• ❌ Backend-only changes (use spring-boot-backend skill)

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Server Management

Check if servers running:

# Check PID files
[ -f scripts/.pid/backend.pid ] && kill -0 $(cat scripts/.pid/backend.pid)
[ -f scripts/.pid/frontend.pid ] && kill -0 $(cat scripts/.pid/frontend.pid)

# Health checks
curl http://localhost:8080/actuator/health  # Backend
curl -I http://localhost:4200               # Frontend

Start servers:

./scripts/start-dev.sh          # Backend + Frontend
./scripts/start-dev.sh --with-db # Include PostgreSQL

When to restart:

• ✅ Code changes (Java/TypeScript modified)
• ✅ Servers not responding (PID dead, ports free)
• ✅ Health checks failing

Rebuild & Restart:

./scripts/stop-dev.sh
cd backend && ./mvnw clean package  # If backend changes
cd frontend && npm run build         # If frontend changes
./scripts/start-dev.sh

→ Full docs: references/server-management.md

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Verification Workflow

5-Step Process

Step 0: Verify Servers Running
   ↓
Step 1: Navigate & Capture State
   ↓
Step 2: Check Console Errors
   ↓
Step 3: Check Network Requests
   ↓
Step 4: Visual Verification
   ↓
Step 5: Report Results

Detailed Steps

Step 0: Verify Servers Running

# Check if servers running (PID + health)
[ -f scripts/.pid/backend.pid ] && kill -0 $(cat scripts/.pid/backend.pid)
[ -f scripts/.pid/frontend.pid ] && kill -0 $(cat scripts/.pid/frontend.pid)

# If NOT running OR code changes → restart
./scripts/stop-dev.sh
./scripts/start-dev.sh

Step 1: Navigate & Capture State

• list_pages() → check open pages
• navigate_page(url: "http://localhost:4200/path") → go to route
• take_snapshot() → accessibility tree (structural check)
• take_screenshot() → visual representation

Step 2: Check Console Errors

• list_console_messages(types: ["error", "warn"]) → filter errors
• get_console_message(msgid: N) → detailed stack trace

Step 3: Check Network Requests

• list_network_requests(resourceTypes: ["xhr", "fetch"]) → API calls
• get_network_request(reqid: N) → headers, payload, response

Step 4: Visual Verification

• take_screenshot(fullPage: true) → full page visual
• resize_page(width, height) → test responsive (375, 768, 1920)
• hover(uid), click(uid) → test interactions

Step 5: Report Results

• ✅ PASS: "All verifications passed. No console errors, API calls 200 OK, UI renders correctly."
• ❌ FAIL: "Issues found: Console error at component.ts:42, Network POST /api/login → 401, Visual: missing padding"

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Key MCP Tools

Navigation:

• list_pages() - list open tabs
• navigate_page(url, timeout) - go to URL
• wait_for(text, timeout) - wait for text to appear

State Capture:

• take_snapshot(verbose) - accessibility tree (fast, text)
• take_screenshot(uid, fullPage, format) - visual capture (PNG/JPEG/WebP)
• evaluate_script(function, args) - execute JS in page

Console & Network:

• list_console_messages(types, pageIdx, pageSize) - get console logs
• get_console_message(msgid) - detailed error info
• list_network_requests(resourceTypes, pageIdx) - list HTTP requests
• get_network_request(reqid) - detailed request/response

Interaction:

• click(uid, dblClick) - click element by UID
• fill(uid, value) - fill input/textarea
• fill_form(elements) - fill multiple fields
• hover(uid) - hover over element

Emulation:

• resize_page(width, height) - change viewport (mobile: 375x667, tablet: 768x1024, desktop: 1920x1080)
• emulate_network(throttlingOption) - simulate network (Offline, Slow 3G, Fast 3G, etc.)
• performance_start_trace(reload, autoStop) - measure Core Web Vitals

→ Full docs: references/mcp-tools-reference.md

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Quick Start

Example 1: Verify Console After Component Implementation

navigate_page(url: "http://localhost:4200/gallery")
list_console_messages(types: ["error", "warn"])
// ✅ No errors → Component works
// ❌ Errors found → get_console_message(msgid) → Fix

Example 2: Verify Network After API Integration

navigate_page(url: "http://localhost:4200/login")
fill_form([{ uid: "input-email", value: "[e-mail]" }, { uid: "input-password", value: "test123456" }])
click(uid: "btn-login")
wait_for(text: "Photo Gallery", timeout: 5000)
list_network_requests(resourceTypes: ["fetch"])
get_network_request(reqid: 1)
// → POST /api/auth/login → 200 OK → JWT token ✅

Example 3: Verify Visual Layout

navigate_page(url: "http://localhost:4200/gallery")
take_screenshot(fullPage: true)
resize_page(width: 375, height: 667)  // Mobile
take_screenshot()
// → Check: Single column layout on mobile ✅

→ Detailed scenarios: examples/*.md → Detailed patterns: references/verification-patterns.md

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Best Practices

1. Always check console first - even if UI looks correct

   list_console_messages(types: ["error", "warn"])
   

2. Check network for API calls - verify status codes, headers, payloads

   list_network_requests(resourceTypes: ["xhr", "fetch"])
   

3. Test responsive layouts - mobile (375), tablet (768), desktop (1920)

   resize_page(width: 375, height: 667)
   

4. Use snapshots for structure, screenshots for visual

   • Snapshot (fast, text) → "Are elements present?"
   • Screenshot (slow, image) → "Does it look right?"

5. Iterative verification for bug fixes

   • Verify bug → Fix code → Re-verify → Repeat until ✅

6. Report actionable issues

   • ❌ BAD: "Login doesn't work"
   • ✅ GOOD: "Login failed: POST /api/auth/login → 401. Request missing Authorization header. Check AuthInterceptor."

7. Restart servers when code changes

   ./scripts/stop-dev.sh && ./scripts/start-dev.sh
   

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Related Skills

• angular-frontend - for implementing Angular components
• spring-boot-backend - for backend API development
• code-review - for code quality checks

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Key Reminders

Proactive Verification:

• ✅ Use after implementing tasks
• ✅ Verify BEFORE marking complete
• ✅ Catch issues early

Comprehensive Checks:

• ✅ Console errors (ALWAYS)
• ✅ Network requests (for API features)
• ✅ Visual rendering (for UI features)
• ✅ Responsive layout (mobile, tablet, desktop)

Server Management:

• ✅ Check servers before starting (PID/health)
• ✅ Restart when code changes
• ✅ Use project scripts (./scripts/start-dev.sh)