# K6 Browser Testing - Future Enhancement

## Overview
K6 browser testing was deferred in Phase 3 due to additional complexity and dependencies. This document outlines what would be needed to add browser testing support in the future.

## Requirements for Browser Testing

### 1. Additional Dependencies
- Chromium or Chrome browser installation
- k6 browser module (experimental)
- Additional GitHub Actions setup for headless browser

### 2. Workflow Changes Needed
```yaml
- name: Setup Chrome
  uses: browser-actions/setup-chrome@latest

- name: Install k6 with browser support
  run: |
    # k6 browser requires different installation
    xk6 build --with github.com/grafana/xk6-browser
```

### 3. Example Browser Test Structure
```javascript
// .github/k6/scripts/browser-test.js
import { chromium } from 'k6/experimental/browser';
import { check, sleep } from 'k6';

export const options = {
  scenarios: {
    browser: {
      executor: 'shared-iterations',
      vus: 1,
      iterations: 10,
      options: {
        browser: {
          type: 'chromium',
        },
      },
    },
  },
  thresholds: {
    browser_web_vital_lcp: ['p(90) < 2500'],
    browser_web_vital_fid: ['p(90) < 100'],
    browser_web_vital_cls: ['p(90) < 0.1'],
  },
};

export default async function () {
  const browser = chromium.launch({
    headless: true,
    timeout: '60s',
  });
  
  const context = browser.newContext();
  const page = context.newPage();
  
  try {
    // Navigate and measure
    await page.goto(__ENV.K6_BASE_URL, { waitUntil: 'networkidle' });
    
    // Capture Core Web Vitals
    const metrics = await page.evaluate(() => ({
      lcp: performance.getEntriesByType('largest-contentful-paint')[0]?.startTime,
      fid: performance.getEntriesByType('first-input')[0]?.processingStart,
      cls: performance.getEntriesByType('layout-shift')
        .reduce((sum, entry) => sum + entry.value, 0),
    }));
    
    check(metrics, {
      'LCP under 2.5s': (m) => m.lcp < 2500,
      'FID under 100ms': (m) => !m.fid || m.fid < 100,
      'CLS under 0.1': (m) => m.cls < 0.1,
    });
    
    // User journey testing
    await page.click('text=Login');
    await page.fill('input[name="username"]', 'testuser');
    await page.fill('input[name="password"]', 'testpass');
    await page.click('button[type="submit"]');
    
    // Wait for navigation
    await page.waitForSelector('.dashboard', { timeout: 5000 });
    
  } finally {
    page.close();
    browser.close();
  }
}
```

## Benefits of Adding Browser Testing

1. **Real User Experience**: Test actual page load and interaction performance
2. **Core Web Vitals**: Measure Google's key metrics (LCP, FID, CLS)
3. **JavaScript Performance**: Test client-side rendering and SPA performance
4. **Visual Testing**: Capture screenshots and visual regressions
5. **User Journey Testing**: Test complete workflows including JS interactions

## Implementation Considerations

1. **Resource Usage**: Browser tests use significantly more resources than HTTP tests
2. **Execution Time**: Browser tests are slower than API tests
3. **Parallelization**: Limited VUs due to browser overhead
4. **Debugging**: More complex to debug in CI/CD environments

## When to Add Browser Testing

Consider adding browser testing when:
- Frontend performance is critical
- You need to measure Core Web Vitals
- Testing SPAs or heavily JavaScript-dependent applications
- User experience metrics are KPIs
- Visual regression testing is needed

## Alternative Approaches

If full browser testing is too heavy, consider:
1. **Synthetic monitoring** - Use external services for browser testing
2. **Lighthouse CI** - Automated Lighthouse tests in CI/CD
3. **Puppeteer/Playwright** - Separate browser testing pipeline
4. **WebPageTest API** - Integration with WebPageTest for detailed metrics

## References

- [k6 Browser Documentation](https://k6.io/docs/using-k6-browser/)
- [k6 Browser Examples](https://github.com/grafana/k6-browser-examples)
- [Core Web Vitals](https://web.dev/vitals/)