Playwright - Browser Automation & E2E Testing
Expert knowledge for browser automation and end-to-end testing with Playwright - a modern cross-browser testing framework.
IMPORTANT - Path Resolution: This skill can be installed in different locations. Before executing commands, determine the skill directory based on where you loaded this SKILL.md file, and use that path in all commands. Replace $SKILL_DIR with the actual discovered path.
Common installation paths:
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Plugin system: ~/.claude/plugins/*/playwright/skills/playwright
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Manual global: ~/.claude/skills/playwright
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Project-specific: <project>/.claude/skills/playwright
CRITICAL WORKFLOW - Follow These Steps
When automating browser tasks:
Auto-detect dev servers - For localhost testing, ALWAYS run server detection FIRST:
cd $SKILL_DIR && node -e "require('./lib/helpers').detectDevServers().then(servers => console.log(JSON.stringify(servers)))"
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If 1 server found: Use it automatically, inform user
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If multiple servers found: Ask user which one to test
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If no servers found: Ask for URL or offer to help start dev server
Write scripts to /tmp - NEVER write test files to skill directory; always use /tmp/playwright-test-*.js
Use visible browser by default - Always use headless: false unless user specifically requests headless mode
Parameterize URLs - Always make URLs configurable via constant at top of script
Execute via run.js - Always run: cd $SKILL_DIR && node run.js /tmp/playwright-test-*.js
Quick Start
First-Time Setup
Navigate to skill directory
cd $SKILL_DIR
Install using bun (preferred)
bun run setup
Or using npm
npm run setup:npm
This installs Playwright and Chromium browser. Only needed once.
Installation (For E2E Testing Projects)
Using Bun (preferred)
bun add -d @playwright/test bunx playwright install
Using npm
npm init playwright@latest
Configuration
// playwright.config.ts import { defineConfig, devices } from '@playwright/test'
export default defineConfig({ testDir: './tests', fullyParallel: true, reporter: 'html', use: { baseURL: 'http://localhost:3000', trace: 'on-first-retry', screenshot: 'only-on-failure', }, projects: [ { name: 'chromium', use: { ...devices['Desktop Chrome'] } }, { name: 'firefox', use: { ...devices['Desktop Firefox'] } }, { name: 'webkit', use: { ...devices['Desktop Safari'] } }, ], webServer: { command: 'bun run dev', url: 'http://localhost:3000', }, })
Browser Automation Patterns
How It Works
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You describe what you want to test/automate
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I auto-detect running dev servers (or ask for URL)
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I write custom Playwright code in /tmp/playwright-test-*.js
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I execute it via: cd $SKILL_DIR && node run.js /tmp/playwright-test-*.js
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Results displayed in real-time, browser window visible
Test a Page (Multiple Viewports)
// /tmp/playwright-test-responsive.js const { chromium } = require('playwright');
const TARGET_URL = 'http://localhost:3001'; // Auto-detected
(async () => { const browser = await chromium.launch({ headless: false, slowMo: 100 }); const page = await browser.newPage();
// Desktop test await page.setViewportSize({ width: 1920, height: 1080 }); await page.goto(TARGET_URL); console.log('Desktop - Title:', await page.title()); await page.screenshot({ path: '/tmp/desktop.png', fullPage: true });
// Mobile test await page.setViewportSize({ width: 375, height: 667 }); await page.screenshot({ path: '/tmp/mobile.png', fullPage: true });
await browser.close(); })();
Execute: cd $SKILL_DIR && node run.js /tmp/playwright-test-responsive.js
Test Login Flow
// /tmp/playwright-test-login.js const { chromium } = require('playwright');
const TARGET_URL = 'http://localhost:3001'; // Auto-detected
(async () => { const browser = await chromium.launch({ headless: false }); const page = await browser.newPage();
await page.goto(${TARGET_URL}/login);
await page.fill('input[name="email"]', 'test@example.com');
await page.fill('input[name="password"]', 'password123');
await page.click('button[type="submit"]');
await page.waitForURL('**/dashboard'); console.log('✅ Login successful, redirected to dashboard');
await browser.close(); })();
Check for Broken Links
const { chromium } = require('playwright');
(async () => { const browser = await chromium.launch({ headless: false }); const page = await browser.newPage();
await page.goto('http://localhost:3000');
const links = await page.locator('a[href^="http"]').all(); const results = { working: 0, broken: [] };
for (const link of links) { const href = await link.getAttribute('href'); try { const response = await page.request.head(href); if (response.ok()) { results.working++; } else { results.broken.push({ url: href, status: response.status() }); } } catch (e) { results.broken.push({ url: href, error: e.message }); } }
console.log(✅ Working links: ${results.working});
console.log(❌ Broken links:, results.broken);
await browser.close(); })();
E2E Testing Patterns
Running Tests
Run all tests
bunx playwright test
Headed mode (see browser)
bunx playwright test --headed
Specific file
bunx playwright test tests/login.spec.ts
Debug mode
bunx playwright test --debug
UI mode (interactive)
bunx playwright test --ui
Specific browser
bunx playwright test --project=chromium
Generate report
bunx playwright show-report
Writing Tests
import { test, expect } from '@playwright/test'
test.describe('Login flow', () => { test('successful login', async ({ page }) => { await page.goto('/') await page.getByRole('link', { name: 'Login' }).click() await page.getByLabel('Email').fill('user@example.com') await page.getByLabel('Password').fill('password123') await page.getByRole('button', { name: 'Sign in' }).click()
await expect(page.getByRole('heading', { name: 'Dashboard' })).toBeVisible()
})
test('shows error for invalid credentials', async ({ page }) => { await page.goto('/login') await page.getByLabel('Email').fill('wrong@example.com') await page.getByLabel('Password').fill('wrongpassword') await page.getByRole('button', { name: 'Sign in' }).click()
await expect(page.getByText('Invalid credentials')).toBeVisible()
}) })
Selectors (Best Practices)
// ✅ Role-based (recommended) await page.getByRole('button', { name: 'Submit' }) await page.getByRole('link', { name: 'Home' })
// ✅ Text/Label await page.getByText('Hello World') await page.getByLabel('Email')
// ✅ Test ID (fallback) await page.getByTestId('submit-button')
// ❌ Avoid CSS selectors (brittle) await page.locator('.btn-primary')
Assertions
// Visibility await expect(page.getByText('Success')).toBeVisible() await expect(page.getByRole('button')).toBeEnabled()
// Text await expect(page.getByRole('heading')).toHaveText('Welcome') await expect(page.getByRole('alert')).toContainText('error')
// Attributes await expect(page.getByRole('link')).toHaveAttribute('href', '/home')
// URL/Title await expect(page).toHaveURL('/dashboard') await expect(page).toHaveTitle('Dashboard')
// Count await expect(page.getByRole('listitem')).toHaveCount(5)
Actions
// Clicking await page.getByRole('button').click() await page.getByText('File').dblclick()
// Typing await page.getByLabel('Email').fill('user@example.com') await page.getByLabel('Search').press('Enter')
// Selecting await page.getByLabel('Country').selectOption('us')
// File Upload await page.getByLabel('Upload').setInputFiles('path/to/file.pdf')
Network Mocking
test('mocks API response', async ({ page }) => { await page.route('**/api/users', async route => { await route.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify([{ id: 1, name: 'Test User' }]), }) })
await page.goto('/users') await expect(page.getByText('Test User')).toBeVisible() })
Visual Testing
test('captures screenshot', async ({ page }) => { await page.goto('/') await page.screenshot({ path: 'screenshot.png', fullPage: true }) await expect(page).toHaveScreenshot('homepage.png') })
Authentication State
// Save state after login setup('authenticate', async ({ page }) => { await page.goto('/login') await page.getByLabel('Email').fill('user@example.com') await page.getByLabel('Password').fill('password123') await page.getByRole('button', { name: 'Sign in' }).click() await page.context().storageState({ path: 'auth.json' }) })
// Reuse in config use: { storageState: 'auth.json' }
Page Object Model
// pages/LoginPage.ts import { Page, Locator } from '@playwright/test'
export class LoginPage { readonly emailInput: Locator readonly passwordInput: Locator readonly submitButton: Locator
constructor(page: Page) { this.emailInput = page.getByLabel('Email') this.passwordInput = page.getByLabel('Password') this.submitButton = page.getByRole('button', { name: 'Sign in' }) }
async login(email: string, password: string) { await this.emailInput.fill(email) await this.passwordInput.fill(password) await this.submitButton.click() } }
// Usage const loginPage = new LoginPage(page) await loginPage.login('user@example.com', 'password123')
Available Helpers
Optional utility functions in lib/helpers.js :
const helpers = require('./lib/helpers');
// Detect running dev servers (CRITICAL - use this first!) const servers = await helpers.detectDevServers(); console.log('Found servers:', servers);
// Safe click with retry await helpers.safeClick(page, 'button.submit', { retries: 3 });
// Safe type with clear await helpers.safeType(page, '#username', 'testuser');
// Take timestamped screenshot await helpers.takeScreenshot(page, 'test-result');
// Handle cookie banners await helpers.handleCookieBanner(page);
// Extract table data const data = await helpers.extractTableData(page, 'table.results');
// Create context with custom headers const context = await helpers.createContext(browser);
Custom HTTP Headers
Configure custom headers for all HTTP requests via environment variables:
Single header (common case)
PW_HEADER_NAME=X-Automated-By PW_HEADER_VALUE=playwright-skill
cd $SKILL_DIR && node run.js /tmp/my-script.js
Multiple headers (JSON format)
PW_EXTRA_HEADERS='{"X-Automated-By":"playwright-skill","X-Debug":"true"}'
cd $SKILL_DIR && node run.js /tmp/my-script.js
Headers are automatically applied when using helpers.createContext() .
Inline Execution (Simple Tasks)
For quick one-off tasks:
cd $SKILL_DIR && node run.js " const browser = await chromium.launch({ headless: false }); const page = await browser.newPage(); await page.goto('http://localhost:3001'); await page.screenshot({ path: '/tmp/quick-screenshot.png', fullPage: true }); console.log('Screenshot saved'); await browser.close(); "
When to use:
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Inline: Quick one-off tasks (screenshot, element check)
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Files: Complex tests, reusable automation
Best Practices
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CRITICAL: Detect servers FIRST - Always run detectDevServers() before writing test code
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Use /tmp for test files - Write to /tmp/playwright-test-*.js , never to skill directory
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Parameterize URLs - Put detected/provided URL in TARGET_URL constant
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DEFAULT: Visible browser - Always use headless: false unless explicitly requested
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Prefer role-based selectors - More stable than CSS selectors
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Trust auto-waiting - No manual sleeps needed
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Each test gets fresh context - Automatic isolation
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Run tests in parallel - Default behavior
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Mock external dependencies - Use page.route()
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Use trace viewer - Time-travel debugging
Tips
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Slow down: Use slowMo: 100 to make actions visible
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Wait strategies: Use waitForURL , waitForSelector , waitForLoadState instead of fixed timeouts
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Error handling: Always use try-catch for robust automation
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Console output: Use console.log() to track progress
Troubleshooting
Playwright not installed:
cd $SKILL_DIR && bun run setup
Module not found: Ensure running from skill directory via run.js wrapper
Browser doesn't open: Check headless: false and ensure display available
Element not found: Add wait: await page.waitForSelector('.element', { timeout: 10000 })
See Also
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vitest-testing
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Unit and integration testing
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api-testing
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HTTP API testing
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test-quality-analysis
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Test quality patterns
When to Load References
Load references/API_REFERENCE.md when you need:
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Advanced selector patterns and locator strategies
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Network interception and request/response mocking
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Authentication patterns and session management
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Visual regression testing setup
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Mobile device emulation configurations
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Performance testing and metrics
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Debugging techniques (trace viewer, inspector)
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CI/CD pipeline integration
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Accessibility testing with axe-core
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Data-driven and parameterized testing
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Page Object Model advanced patterns
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Parallel execution strategies