visual-testing-advanced

# Advanced Visual Testing <default_to_action> When detecting visual regressions or validating UI: 1. CAPTURE baseline screenshots (first run establishes baseline) 2. COMPARE new screenshots against baseline (pixel-by-pixel or AI) 3. MASK dynamic content (timestamps, ads, user counts) 4. TEST across devices (desktop, tablet, mobile viewports) 5. REVIEW and approve intentional changes, fail on regressions **Quick Visual Testing Steps:** - Set up baseline on main branch - Compare feature branch against baseline - Mask dynamic elements (timestamps, avatars) - Use AI-powered comparison to reduce false positives - Integrate in CI/CD to block visual regressions **Critical Success Factors:** - Functional tests don't catch visual bugs - AI-powered tools reduce false positives - Review diffs, don't just auto-approve </default_to_action> ## Quick Reference Card ### When to Use - UI component changes - CSS/styling modifications - Responsive design validation - Cross-browser consistency checks ### Visual Bug Types | Bug Type | Description | |----------|-------------| | Layout shift | Elements moved position | | Color change | Unintended color modification | | Font rendering | Typography issues | | Alignment | Spacing/alignment problems | | Missing images | Broken image paths | | Overflow | Content clipping | ### Comparison Algorithms | Algorithm | Best For | |-----------|----------| | **Pixel diff** | Exact match requirement | | **Structural similarity** | Handle anti-aliasing | | **AI semantic** | Ignore insignificant changes | --- ## Visual Regression with Playwright ```javascript import { test, expect } from '@playwright/test'; test('homepage visual regression', async ({ page }) => { await page.goto('https://example.com'); // Capture and compare screenshot await expect(page).toHaveScreenshot('homepage.png'); // First run: saves baseline // Subsequent runs: compares to baseline }); test('responsive design', async ({ page }) => { // Mobile viewport await page.setViewportSize({ width: 375, height: 667 }); await page.goto('https://example.com'); await expect(page).toHaveScreenshot('homepage-mobile.png'); // Tablet viewport await page.setViewportSize({ width: 768, height: 1024 }); await expect(page).toHaveScreenshot('homepage-tablet.png'); }); ``` --- ## Handling Dynamic Content ```javascript test('mask dynamic elements', async ({ page }) => { await page.goto('https://example.com'); await expect(page).toHaveScreenshot({ mask: [ page.locator('.timestamp'), // Dynamic time page.locator('.user-count'), // Live counter page.locator('.advertisement'), // Ads page.locator('.avatar') // User avatars ] }); }); ``` --- ## AI-Powered Visual Testing (Percy) ```javascript import percySnapshot from '@percy/playwright'; test('AI-powered visual test', async ({ page }) => { await page.goto('https://example.com'); // Percy uses AI to ignore anti-aliasing, minor font differences await percySnapshot(page, 'Homepage'); }); test('component visual test', async ({ page }) => { await page.goto('https://example.com/components'); // Snapshot specific component const button = page.locator('.primary-button'); await percySnapshot(page, 'Primary Button', { scope: button }); }); ``` --- ## Playwright Configuration ```javascript // playwright.config.js export default { expect: { toHaveScreenshot: { maxDiffPixels: 100, // Allow 100 pixel difference maxDiffPixelRatio: 0.01, // Or 1% of image threshold: 0.2, // Color similarity threshold animations: 'disabled', // Disable animations caret: 'hide' // Hide cursor } } }; ``` --- ## Agent-Driven Visual Testing ```typescript // Comprehensive visual regression await Task("Visual Regression Suite", { baseline: 'main-branch', current: 'feature-branch', pages: ['homepage', 'product', 'checkout'], devices: ['desktop', 'tablet', 'mobile'], browsers: ['chrome', 'firefox', 'safari'], threshold: 0.01 }, "qe-visual-tester"); // Returns: // { // comparisons: 27, // 3 pages × 3 devices × 3 browsers // differences: 2, // report: 'visual-regression-report.html' // } ``` --- ## Agent Coordination Hints ### Memory Namespace ``` aqe/visual-testing/ ├── baselines/* - Baseline screenshots ├── comparisons/* - Diff results ├── components/* - Component snapshots └── reports/* - Visual regression reports ``` ### Fleet Coordination ```typescript const visualFleet = await FleetManager.coordinate({ strategy: 'visual-testing', agents: [ 'qe-visual-tester', // Screenshot comparison 'qe-test-executor', // Cross-browser execution 'qe-quality-gate' // Block on visual regressions ], topology: 'parallel' }); ``` --- ## Related Skills - [accessibility-testing](../accessibility-testing/) - Visual a11y checks - [compatibility-testing](../compatibility-testing/) - Cross-browser visuals - [regression-testing](../regression-testing/) - Regression suite --- ## Remember **Functional tests don't catch visual bugs.** Layout shifts, color changes, font rendering, alignment issues - all invisible to functional tests but visible to users. **AI-powered tools reduce false positives.** Percy, Applitools use AI to ignore insignificant differences (anti-aliasing, minor font rendering). **With Agents:** `qe-visual-tester` automates visual regression across browsers and devices, uses AI to filter noise, and generates visual diff reports. Catches UI regressions before users see them.