Web Application Testing

When to Use This Skill

• Test frontend functionality in a real browser
• Verify UI behavior and interactions
• Debug web application issues
• Capture screenshots for documentation or debugging
• Inspect browser console logs
• Validate form submissions and user flows
• Check responsive design across viewports

Prerequisites

• Node.js installed on the system
• A locally running web application (or accessible URL)
• Playwright will be installed automatically if not present

Core Capabilities

1. Browser Automation

• Navigate to URLs
• Click buttons and links
• Fill form fields
• Select dropdowns
• Handle dialogs and alerts

2. Verification

• Assert element presence
• Verify text content
• Check element visibility
• Validate URLs
• Test responsive behavior

3. Debugging

• Capture screenshots
• View console logs
• Inspect network requests
• Debug failed tests

Usage Examples

Example 1: Basic Navigation Test

// Navigate to a page and verify title
await page.goto('http://localhost:3000');
const title = await page.title();
console.log('Page title:', title);

Example 2: Form Interaction

// Fill out and submit a form
await page.fill('#username', 'testuser');
await page.fill('#password', 'password123');
await page.click('button[type="submit"]');
await page.waitForURL('**/dashboard');

Example 3: Screenshot Capture

// Capture a screenshot for debugging
await page.screenshot({ path: 'debug.png', fullPage: true });

Guidelines

1. Always verify the app is running - Check that the local server is accessible before running tests
2. Use explicit waits - Wait for elements or navigation to complete before interacting
3. Capture screenshots on failure - Take screenshots to help debug issues
4. Clean up resources - Always close the browser when done
5. Handle timeouts gracefully - Set reasonable timeouts for slow operations
6. Test incrementally - Start with simple interactions before complex flows
7. Use selectors wisely - Prefer data-testid or role-based selectors over CSS classes

Common Patterns

Pattern: Wait for Element

await page.waitForSelector('#element-id', { state: 'visible' });

Pattern: Check if Element Exists

const exists = await page.locator('#element-id').count() > 0;

Pattern: Get Console Logs

page.on('console', msg => console.log('Browser log:', msg.text()));

Pattern: Handle Errors

try {
  await page.click('#button');
} catch (error) {
  await page.screenshot({ path: 'error.png' });
  throw error;
}

Limitations

• Requires Node.js environment
• Cannot test native mobile apps (use React Native Testing Library instead)
• May have issues with complex authentication flows
• Some modern frameworks may require specific configuration