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From agentic-bundle-aas-qa-test-automation
Guides Playwright and Puppeteer usage for web testing, scraping, and agent automation with anti-detection strategies.
How this skill is triggered — by the user, by Claude, or both
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/agentic-bundle-aas-qa-test-automation:browser-automationThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
Browser automation powers web testing, scraping, and AI agent interactions.
Browser automation powers web testing, scraping, and AI agent interactions. The difference between a flaky script and a reliable system comes down to understanding selectors, waiting strategies, and anti-detection patterns.
This skill covers Playwright (recommended) and Puppeteer, with patterns for testing, scraping, and agentic browser control. Key insight: Playwright won the framework war. Unless you need Puppeteer's stealth ecosystem or are Chrome-only, Playwright is the better choice in 2025.
Critical distinction: Testing automation (predictable apps you control) vs scraping/agent automation (unpredictable sites that fight back). Different problems, different solutions.
Each test runs in complete isolation with fresh state
When to use: Testing, any automation that needs reproducibility
""" Each test gets its own:
""" import { test, expect } from '@playwright/test';
// Each test runs in isolated browser context test('user can add item to cart', async ({ page }) => { // Fresh context - no cookies, no storage from other tests await page.goto('/products'); await page.getByRole('button', { name: 'Add to Cart' }).click(); await expect(page.getByTestId('cart-count')).toHaveText('1'); });
test('user can remove item from cart', async ({ page }) => { // Completely isolated - cart is empty await page.goto('/cart'); await expect(page.getByText('Your cart is empty')).toBeVisible(); }); """
""" // Save auth state once, reuse across tests // setup.ts import { test as setup } from '@playwright/test';
setup('authenticate', async ({ page }) => { await page.goto('/login'); await page.getByLabel('Email').fill('[email protected]'); await page.getByLabel('Password').fill('password'); await page.getByRole('button', { name: 'Sign in' }).click();
// Wait for auth to complete await page.waitForURL('/dashboard');
// Save authentication state await page.context().storageState({ path: './playwright/.auth/user.json' }); });
// playwright.config.ts export default defineConfig({ projects: [ { name: 'setup', testMatch: /.*.setup.ts/ }, { name: 'tests', dependencies: ['setup'], use: { storageState: './playwright/.auth/user.json', }, }, ], }); """
Select elements the way users see them
When to use: Always - the default approach for selectors
""" Priority order:
""" // By role - THE BEST CHOICE await page.getByRole('button', { name: 'Submit' }).click(); await page.getByRole('link', { name: 'Sign up' }).click(); await page.getByRole('heading', { name: 'Dashboard' }).isVisible(); await page.getByRole('textbox', { name: 'Search' }).fill('query');
// By text content await page.getByText('Welcome back').isVisible(); await page.getByText(/Order #\d+/).click(); // Regex supported
// By label (forms) await page.getByLabel('Email address').fill('[email protected]'); await page.getByLabel('Password').fill('secret');
// By placeholder await page.getByPlaceholder('Search...').fill('query');
// By test ID (when no user-facing option works) await page.getByTestId('submit-button').click(); """
""" // DON'T - CSS selectors tied to structure await page.locator('.btn-primary.submit-form').click(); await page.locator('#header > div > button:nth-child(2)').click();
// DON'T - XPath tied to structure await page.locator('//div[@class="form"]/button[1]').click();
// DON'T - Auto-generated selectors await page.locator('[data-v-12345]').click(); """
""" // Filter by containing text await page.getByRole('listitem') .filter({ hasText: 'Product A' }) .getByRole('button', { name: 'Add to cart' }) .click();
// Filter by NOT containing await page.getByRole('listitem') .filter({ hasNotText: 'Sold out' }) .first() .click();
// Chain locators const row = page.getByRole('row', { name: 'John Doe' }); await row.getByRole('button', { name: 'Edit' }).click(); """
Let Playwright wait automatically, never add manual waits
When to use: Always with Playwright
""" Playwright waits automatically for:
NEVER add manual waits! """
""" // DON'T DO THIS await page.goto('/dashboard'); await page.waitForTimeout(2000); // NO! Arbitrary wait await page.click('.submit-button');
// DON'T DO THIS await page.waitForSelector('.loading-spinner', { state: 'hidden' }); await page.waitForTimeout(500); // "Just to be safe" - NO! """
""" // Auto-waits for button to be clickable await page.getByRole('button', { name: 'Submit' }).click();
// Auto-waits for text to appear await expect(page.getByText('Success!')).toBeVisible();
// Auto-waits for navigation to complete await page.goto('/dashboard'); // Page is ready - no manual wait needed """
""" // Wait for specific network request const responsePromise = page.waitForResponse( response => response.url().includes('/api/data') ); await page.getByRole('button', { name: 'Load' }).click(); const response = await responsePromise;
// Wait for URL change await Promise.all([ page.waitForURL('**/dashboard'), page.getByRole('button', { name: 'Login' }).click(), ]);
// Wait for download const downloadPromise = page.waitForEvent('download'); await page.getByText('Export CSV').click(); const download = await downloadPromise; """
Avoid bot detection for scraping
When to use: Scraping sites with anti-bot protection
""" Bot detection checks for:
""" import puppeteer from 'puppeteer-extra'; import StealthPlugin from 'puppeteer-extra-plugin-stealth';
puppeteer.use(StealthPlugin());
const browser = await puppeteer.launch({ headless: 'new', args: [ '--no-sandbox', '--disable-setuid-sandbox', '--disable-blink-features=AutomationControlled', ], });
const page = await browser.newPage();
// Set realistic viewport await page.setViewport({ width: 1920, height: 1080 });
// Realistic user agent await page.setUserAgent( 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 ' + '(KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36' );
// Navigate with human-like behavior await page.goto('https://target-site.com', { waitUntil: 'networkidle0', }); """
""" import { chromium } from 'playwright-extra'; import stealth from 'puppeteer-extra-plugin-stealth';
chromium.use(stealth());
const browser = await chromium.launch({ headless: true }); const context = await browser.newContext({ viewport: { width: 1920, height: 1080 }, userAgent: 'Mozilla/5.0 ...', locale: 'en-US', timezoneId: 'America/New_York', }); """
""" // Random delays between actions const randomDelay = (min: number, max: number) => new Promise(r => setTimeout(r, Math.random() * (max - min) + min));
await page.goto(url); await randomDelay(500, 1500);
// Mouse movement before click const button = await page.$('button.submit'); const box = await button.boundingBox(); await page.mouse.move( box.x + box.width / 2, box.y + box.height / 2, { steps: 10 } // Move in steps like a human ); await randomDelay(100, 300); await button.click();
// Scroll naturally await page.evaluate(() => { window.scrollBy({ top: 300 + Math.random() * 200, behavior: 'smooth' }); }); """
Handle failures gracefully with screenshots and retries
When to use: Any production automation
""" // playwright.config.ts export default defineConfig({ use: { screenshot: 'only-on-failure', trace: 'retain-on-failure', video: 'retain-on-failure', }, retries: 2, // Retry failed tests }); """
""" async function scrapeProduct(page: Page, url: string) { try { await page.goto(url, { timeout: 30000 });
const title = await page.getByRole('heading', { level: 1 }).textContent();
const price = await page.getByTestId('price').textContent();
return { title, price, success: true };
} catch (error) {
// Capture debug info
const screenshot = await page.screenshot({
path: errors/${Date.now()}-error.png,
fullPage: true
});
const html = await page.content();
await fs.writeFile(`errors/${Date.now()}-page.html`, html);
console.error({
url,
error: error.message,
currentUrl: page.url(),
});
return { success: false, error: error.message };
} } """
""" async function withRetry( fn: () => Promise, maxRetries = 3, baseDelay = 1000 ): Promise { let lastError: Error;
for (let attempt = 0; attempt < maxRetries; attempt++) { try { return await fn(); } catch (error) { lastError = error;
if (attempt < maxRetries - 1) {
const delay = baseDelay * Math.pow(2, attempt);
const jitter = delay * 0.1 * Math.random();
await new Promise(r => setTimeout(r, delay + jitter));
}
}
}
throw lastError; }
// Usage const result = await withRetry( () => scrapeProduct(page, url), 3, 2000 ); """
Run tests/tasks in parallel for speed
When to use: Multiple independent pages or tests
""" // playwright.config.ts export default defineConfig({ fullyParallel: true, workers: process.env.CI ? 4 : undefined, // CI: 4 workers, local: CPU-based
projects: [ { name: 'chromium', use: { ...devices['Desktop Chrome'] } }, { name: 'firefox', use: { ...devices['Desktop Firefox'] } }, { name: 'webkit', use: { ...devices['Desktop Safari'] } }, ], }); """
""" const browser = await chromium.launch();
const urls = ['url1', 'url2', 'url3', 'url4', 'url5'];
// Create multiple contexts - each is isolated const results = await Promise.all( urls.map(async (url) => { const context = await browser.newContext(); const page = await context.newPage();
try {
await page.goto(url);
const data = await extractData(page);
return { url, data, success: true };
} catch (error) {
return { url, error: error.message, success: false };
} finally {
await context.close();
}
}) );
await browser.close(); """
""" import pLimit from 'p-limit';
const limit = pLimit(5); // Max 5 concurrent
const results = await Promise.all( urls.map(url => limit(async () => { const context = await browser.newContext(); const page = await context.newPage();
// Random delay between requests
await new Promise(r => setTimeout(r, Math.random() * 2000));
try {
return await scrapePage(page, url);
} finally {
await context.close();
}
})) ); """
Mock, block, or modify network requests
When to use: Testing, blocking ads/analytics, modifying responses
""" await page.route('**/*', (route) => { const url = route.request().url(); const resourceType = route.request().resourceType();
// Block images, fonts, analytics for faster scraping if (['image', 'font', 'media'].includes(resourceType)) { return route.abort(); }
// Block tracking/analytics if (url.includes('google-analytics') || url.includes('facebook.com/tr')) { return route.abort(); }
return route.continue(); }); """
""" await page.route('**/api/products', async (route) => { await route.fulfill({ status: 200, contentType: 'application/json', body: JSON.stringify([ { id: 1, name: 'Mock Product', price: 99.99 }, ]), }); });
// Now page will receive mocked data await page.goto('/products'); """
""" const apiResponses: any[] = [];
page.on('response', async (response) => { if (response.url().includes('/api/')) { const data = await response.json().catch(() => null); apiResponses.push({ url: response.url(), status: response.status(), data, }); } });
await page.goto('/dashboard'); // apiResponses now contains all API calls """
Severity: CRITICAL
Situation: Waiting for elements or page state
Symptoms: Tests pass locally, fail in CI. Pass 9 times, fail on the 10th. "Element not found" errors that seem random. Tests take 30+ seconds when they should take 3.
Why this breaks: waitForTimeout is a fixed delay. If the page loads in 500ms, you wait 2000ms anyway. If the page takes 2100ms (CI is slower), you fail. There's no correct value - it's always either too short or too long.
Recommended fix:
await page.goto('/dashboard'); await page.waitForTimeout(2000); # Arbitrary! await page.click('.submit');
await page.goto('/dashboard'); await page.getByRole('button', { name: 'Submit' }).click();
await expect(page.getByText('Dashboard')).toBeVisible(); await page.waitForURL('**/dashboard'); await page.waitForResponse(resp => resp.url().includes('/api/data'));
await page.getByRole('button').click(); # Auto-waits for stable
Severity: HIGH
Situation: Selecting elements for interaction
Symptoms: Tests break after CSS refactoring. Selectors like .btn-primary stop working. Frontend redesign breaks all tests without changing behavior.
Why this breaks: CSS class names are implementation details for styling, not semantic meaning. When designers change from .btn-primary to .button--primary, your tests break even though behavior is identical.
Recommended fix:
await page.locator('.btn-primary.submit-form').click(); await page.locator('#sidebar > div.menu > ul > li:nth-child(3)').click();
await page.getByRole('button', { name: 'Submit' }).click(); await page.getByRole('menuitem', { name: 'Settings' }).click();
Submit
await page.getByTestId('submit-order').click();
Severity: HIGH
Situation: Scraping sites with bot detection
Symptoms: Immediate 403 errors. CAPTCHA challenges. Empty pages. "Access Denied" messages. Works for 1 request, then gets blocked.
Why this breaks: By default, headless browsers set navigator.webdriver = true. This is the first thing bot detection checks. It's a bright red flag that says "I'm automated."
Recommended fix:
import puppeteer from 'puppeteer-extra'; import StealthPlugin from 'puppeteer-extra-plugin-stealth';
puppeteer.use(StealthPlugin());
const browser = await puppeteer.launch({ headless: 'new', args: ['--disable-blink-features=AutomationControlled'], });
import { chromium } from 'playwright-extra'; import stealth from 'puppeteer-extra-plugin-stealth';
chromium.use(stealth());
await page.evaluateOnNewDocument(() => { Object.defineProperty(navigator, 'webdriver', { get: () => undefined, }); });
Severity: HIGH
Situation: Running multiple tests in sequence
Symptoms: Tests pass individually but fail when run together. Order matters - test B fails if test A runs first. Random failures that "fix themselves" on rerun.
Why this breaks: Shared browser context means shared cookies, localStorage, and session state. Test A logs in, test B expects logged-out state. Test A adds item to cart, test B's cart count is wrong.
Recommended fix:
test('first test', async ({ page }) => { // Fresh context, fresh page });
test('second test', async ({ page }) => { // Completely isolated from first test });
const context = await browser.newContext(); // Fresh context const page = await context.newPage(); // ... test code ... await context.close(); // Clean up
// 1. Save auth state to file await context.storageState({ path: './auth.json' });
// 2. Reuse in other tests const context = await browser.newContext({ storageState: './auth.json' });
Severity: MEDIUM
Situation: Debugging test failures in CI
Symptoms: "Test failed in CI" with no useful information. Can't reproduce locally. Screenshot shows page but not what went wrong. Guessing at root cause.
Why this breaks: CI runs headless on different hardware. Timing is different. Network is different. Without traces, you can't see what actually happened - the sequence of actions, network requests, console logs.
Recommended fix:
export default defineConfig({ use: { trace: 'retain-on-failure', # Keep trace on failure screenshot: 'only-on-failure', # Screenshot on failure video: 'retain-on-failure', # Video on failure }, outputDir: './test-results', });
npx playwright show-trace test-results/path/to/trace.zip
Severity: MEDIUM
Situation: Running tests in headless mode for CI
Symptoms: Works perfectly when you watch it. Fails mysteriously in CI. "Element not visible" in headless but visible in headed mode.
Why this breaks: Headless browsers have no display, which affects some CSS (visibility calculations), viewport sizing, and font rendering. Some animations behave differently. Popup windows may not work.
Recommended fix:
const browser = await chromium.launch({ headless: true, });
const context = await browser.newContext({ viewport: { width: 1280, height: 720 }, });
export default defineConfig({ use: { viewport: { width: 1280, height: 720 }, }, });
npx playwright test --headed
npx playwright test --headed --slowmo 100
npx playwright show-trace trace.zip
await page.screenshot({ path: 'debug.png', fullPage: true });
Severity: HIGH
Situation: Scraping multiple pages quickly
Symptoms: Works for first 50 pages, then 429 errors. Suddenly all requests fail. IP gets blocked. CAPTCHA starts appearing after successful requests.
Why this breaks: Sites monitor request patterns. 100 requests per second from one IP is obviously automated. Rate limits protect servers and catch scrapers.
Recommended fix:
const randomDelay = () => new Promise(r => setTimeout(r, 1000 + Math.random() * 2000));
for (const url of urls) { await randomDelay(); // 1-3 second delay await page.goto(url); // ... scrape ... }
const proxies = ['http://proxy1:8080', 'http://proxy2:8080']; let proxyIndex = 0;
const getNextProxy = () => proxies[proxyIndex++ % proxies.length];
const context = await browser.newContext({ proxy: { server: getNextProxy() }, });
import pLimit from 'p-limit'; const limit = pLimit(3); // Max 3 concurrent
await Promise.all( urls.map(url => limit(() => scrapePage(url))) );
const userAgents = [ 'Mozilla/5.0 (Windows...', 'Mozilla/5.0 (Macintosh...', ];
await page.setExtraHTTPHeaders({ 'User-Agent': userAgents[Math.floor(Math.random() * userAgents.length)] });
Severity: MEDIUM
Situation: Clicking links that open new windows
Symptoms: Click button, nothing happens. Test hangs. "Window not found" errors. Actions succeed but verification fails because you're on wrong page.
Why this breaks: target="_blank" links open new windows. Your page reference still points to the original page. The new window exists but you're not listening for it.
Recommended fix:
const pagePromise = context.waitForEvent('page'); await page.getByRole('link', { name: 'Open in new tab' }).click(); const newPage = await pagePromise; await newPage.waitForLoadState();
// Now interact with new page await expect(newPage.getByRole('heading')).toBeVisible();
// Close when done await newPage.close();
const popupPromise = page.waitForEvent('popup'); await page.getByRole('button', { name: 'Open popup' }).click(); const popup = await popupPromise; await popup.waitForLoadState();
const pages = context.pages(); // Get all open pages
Severity: MEDIUM
Situation: Page contains embedded iframes
Symptoms: Element clearly visible but "not found". Selector works in DevTools but not in Playwright. Parent page selectors work, iframe content doesn't.
Why this breaks: iframes are separate documents. page.locator only searches the main frame. You need to explicitly get the iframe's frame to interact with its contents.
Recommended fix:
const frame = page.frame('payment-iframe'); await frame.getByRole('textbox', { name: 'Card number' }).fill('4242...');
const frame = page.frameLocator('iframe#payment'); await frame.getByRole('textbox', { name: 'Card number' }).fill('4242...');
const outer = page.frameLocator('iframe#outer'); const inner = outer.frameLocator('iframe#inner'); await inner.getByRole('button').click();
await page.waitForSelector('iframe#payment'); const frame = page.frameLocator('iframe#payment'); await frame.getByText('Secure Payment').waitFor();
Severity: ERROR
waitForTimeout causes flaky tests and slow execution
Message: Using waitForTimeout - remove it. Playwright auto-waits for elements. Use waitForResponse, waitForURL, or assertions instead.
Severity: WARNING
setTimeout is unreliable for timing in tests
Message: Using setTimeout instead of Playwright waits. Replace with await expect(...).toBeVisible() or page.waitFor*.
Severity: WARNING
Sleep functions indicate improper waiting strategy
Message: Custom sleep function detected. Use Playwright's built-in waiting mechanisms instead.
Severity: WARNING
CSS class selectors are fragile
Message: Using CSS class selector. Prefer getByRole, getByText, getByLabel, or getByTestId for more stable selectors.
Severity: WARNING
Position-based selectors are very fragile
Message: Using position-based selector. These break when DOM order changes. Use user-facing locators instead.
Severity: INFO
XPath should be last resort
Message: Using XPath selector. Consider getByRole, getByText first. XPath should be last resort for complex DOM traversal.
Severity: WARNING
Framework-generated selectors are extremely fragile
Message: Using auto-generated selector. These change on every build. Use data-testid instead.
Severity: INFO
Scraping without stealth is easily detected
Message: Using Puppeteer without stealth plugin. Consider puppeteer-extra-plugin-stealth for anti-detection.
Severity: INFO
navigator.webdriver exposes automation
Message: Launching browser without hiding automation flags. For scraping, add stealth measures.
Severity: WARNING
One failure shouldn't crash entire scrape
Message: Scraping loop without try/catch. One page failure will crash the entire scrape. Add error handling.
Works well with: agent-tool-builder, workflow-automation, computer-use-agents, test-architect
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First indexed Jun 3, 2026
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Guides Playwright and Puppeteer usage for web testing, scraping, and agent automation with anti-detection strategies.
Guides browser automation with Playwright and Puppeteer for testing, scraping, and AI agent interactions. Covers selectors, waiting strategies, anti-detection, and test isolation patterns.
Provides Playwright and Puppeteer patterns for web testing, scraping, and agentic browser control, with guidance on selectors, waiting strategies, and anti-detection.