Web Tester

Browser-based UI testing and E2E automation.

When to Use

✅ USE this skill when:

• Testing web page functionality (click, fill, navigate)
• Writing E2E test scripts (Playwright/Selenium)
• Taking screenshots for visual regression
• Validating page content, forms, navigation
• Accessibility testing
• "帮我测试这个页面" / "写个E2E自动化脚本"

❌ DON'T use this skill when:

• API testing → use api-tester
• Mobile app testing → use dedicated mobile tools
• Load/stress testing → use k6/JMeter/locust

Quick Start: Playwright

One-shot Page Test

# Navigate and screenshot
npx -y playwright@latest test --browser=chromium -g "test name"

# Or write inline script
node -e "
const { chromium } = require('playwright');
(async () => {
  const browser = await chromium.launch({ headless: true });
  const page = await browser.newPage();
  await page.goto('https://example.com');
  console.log('Title:', await page.title());
  await page.screenshot({ path: '/tmp/screenshot.png' });
  await browser.close();
})();
"

Generate Playwright Test Script

When user provides a page URL and test scenario, generate:

// tests/example.spec.js
const { test, expect } = require('@playwright/test');

test.describe('Login Page Tests', () => {

  test('TC001: Successful login', async ({ page }) => {
    await page.goto('https://app.example.com/login');

    // Fill form
    await page.fill('input[name="username"]', 'admin');
    await page.fill('input[name="password"]', 'Admin@123');
    await page.click('button[type="submit"]');

    // Verify redirect
    await expect(page).toHaveURL(/dashboard/);
    await expect(page.locator('h1')).toContainText('Welcome');
  });

  test('TC002: Login with empty fields', async ({ page }) => {
    await page.goto('https://app.example.com/login');
    await page.click('button[type="submit"]');

    // Verify validation messages
    await expect(page.locator('.error-message')).toBeVisible();
  });

  test('TC003: Login with wrong password', async ({ page }) => {
    await page.goto('https://app.example.com/login');
    await page.fill('input[name="username"]', 'admin');
    await page.fill('input[name="password"]', 'wrongpass');
    await page.click('button[type="submit"]');

    await expect(page.locator('.error-alert')).toContainText('Invalid');
  });
});

Run tests:

# Install Playwright browsers (first time)
npx playwright install chromium

# Run tests
npx playwright test tests/example.spec.js --reporter=list

# Run with headed browser (visible)
npx playwright test --headed

# Run specific test
npx playwright test -g "TC001"

# Generate HTML report
npx playwright test --reporter=html
npx playwright show-report

Common UI Test Patterns

Element Locator Strategies (priority order)

1. data-testid attribute (most stable)
2. role + accessible name
3. placeholder / label text
4. CSS selector
5. XPath (last resort)

// Preferred
page.getByTestId('submit-btn')
page.getByRole('button', { name: 'Submit' })
page.getByPlaceholder('Enter email')
page.getByLabel('Username')

// Fallback
page.locator('button.submit-btn')
page.locator('//button[contains(text(),"Submit")]')

Wait Strategies

// Wait for element
await page.waitForSelector('.result-list');

// Wait for navigation
await page.waitForURL('**/dashboard');

// Wait for network idle
await page.waitForLoadState('networkidle');

// Wait for specific response
const response = await page.waitForResponse('**/api/users');

Screenshot & Visual Comparison

// Full page screenshot
await page.screenshot({ path: 'full-page.png', fullPage: true });

// Element screenshot
await page.locator('.chart').screenshot({ path: 'chart.png' });

// Visual comparison (Playwright built-in)
await expect(page).toHaveScreenshot('homepage.png');

Test Scenarios Checklist

For any web page, consider testing:

Category	Test Points
Navigation	Links work, breadcrumbs correct, back button, deep links
Forms	Required fields, validation messages, submit, reset
Auth	Login, logout, session expiry, role-based access
Responsive	Mobile viewport, tablet, desktop breakpoints
Accessibility	Tab order, screen reader, color contrast, ARIA
Error States	404 page, network error, empty state, timeout
Data Display	Pagination, sorting, filtering, search
File Operations	Upload, download, preview

Accessibility Quick Check

// Install axe-core for a11y testing
// npm install @axe-core/playwright

const { test, expect } = require('@playwright/test');
const AxeBuilder = require('@axe-core/playwright').default;

test('accessibility scan', async ({ page }) => {
  await page.goto('https://example.com');
  const results = await new AxeBuilder({ page }).analyze();
  expect(results.violations).toEqual([]);
});

Tips

• Always use headless: true in CI environments
• Set reasonable timeouts (default 30s is often too long)
• Use page.waitForLoadState('networkidle') before assertions
• For flaky tests: add retries in config, not in test code
• Screenshot on failure is invaluable for debugging

Selenium (Python) Reference

When Playwright is not available or user prefers Selenium:

"""Selenium E2E Test Example"""
import pytest
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.chrome.options import Options

@pytest.fixture
def driver():
    opts = Options()
    opts.add_argument('--headless')
    opts.add_argument('--no-sandbox')
    opts.add_argument('--disable-dev-shm-usage')
    d = webdriver.Chrome(options=opts)
    d.implicitly_wait(10)
    yield d
    d.quit()

class TestLogin:
    def test_successful_login(self, driver):
        driver.get('https://app.example.com/login')
        driver.find_element(By.NAME, 'username').send_keys('admin')
        driver.find_element(By.NAME, 'password').send_keys('Admin@123')
        driver.find_element(By.CSS_SELECTOR, 'button[type=submit]').click()

        WebDriverWait(driver, 10).until(
            EC.url_contains('/dashboard')
        )
        assert 'dashboard' in driver.current_url

    def test_screenshot_on_failure(self, driver):
        driver.get('https://app.example.com/broken-page')
        driver.save_screenshot('/tmp/failure.png')

Install: pip install selenium webdriver-manager

Playwright vs Selenium — When to Choose

维度	Playwright	Selenium
安装	npx playwright install 一键搞定	需要 WebDriver + 浏览器匹配
速度	更快（原生 CDP/WebSocket）	较慢（HTTP 协议通信）
自动等待	内置智能等待	需手动写 WebDriverWait
多浏览器	Chromium/Firefox/WebKit	Chrome/Firefox/Edge/Safari
语言	JS/TS/Python/Java/.NET	Python/Java/C#/Ruby/JS
适合	新项目、快速验证、CI	已有 Selenium 框架的团队

建议: 新项目优先 Playwright，已有 Selenium 资产的项目继续用 Selenium。