Playwright E2E Testing (TypeScript)

Comprehensive toolkit for end-to-end testing of web applications using Playwright with TypeScript. Enables robust UI testing, API validation, and responsive design verification following best practices.

Activation: This skill is triggered when working with Playwright tests, browser automation, E2E testing, API testing with Playwright, or test infrastructure setup.

When to Use This Skill

• Write E2E tests for user flows, forms, navigation, and authentication
• API testing via request fixture or network interception during UI tests
• Responsive testing across mobile, tablet, and desktop viewports
• Debug flaky tests using traces, screenshots, videos, and Playwright Inspector
• Setup test infrastructure with Page Object Model and fixtures
• Mock/intercept APIs for isolated, deterministic testing
• Visual regression testing with screenshot comparisons

Prerequisites

Quick Setup

# Initialize new project
npm init playwright@latest

# Or add to existing project
npm install -D @playwright/test
npx playwright install

First Questions to Ask

Before writing tests, clarify:

1. App URL: Local dev server command + port, or staging URL?
2. Critical flows: Which user journeys must be covered (happy path + error states)?
3. Browsers/devices: Chrome, Firefox, Safari? Mobile viewports?
4. API strategy: Real backend, mocked responses, or hybrid?
5. Test data: Seed data available? Reset/cleanup strategy?

Core Principles

1. Test Runner & TypeScript

Always use @playwright/test with TypeScript for type safety and better IDE support.

import { test, expect } from '@playwright/test';

test('user can login', async ({ page }) => {
  await page.goto('/login');
  await page.getByLabel('Email').fill('user@test.com');
  await page.getByLabel('Password').fill('password123');
  await page.getByRole('button', { name: 'Sign in' }).click();
  await expect(page).toHaveURL(/.*dashboard/);
});

2. Locator Strategy (Priority Order)

See Locator Strategies Guide for detailed patterns.

3. Auto-Waiting & Web-First Assertions

Playwright auto-waits for elements. Never use sleep() or arbitrary timeouts.

// ✅ Web-first assertions (auto-retry)
await expect(page.getByRole('alert')).toBeVisible();
await expect(page).toHaveURL(/dashboard/);
await expect(page.getByTestId('status')).toHaveText('Success!');

// ❌ Avoid manual waits
await page.waitForTimeout(2000); // Bad practice

4. Test Structure with Steps

Use test.step() for readable reports and failure localization:

test('checkout flow', async ({ page }) => {
  await test.step('Add item to cart', async () => {
    await page.goto('/products/1');
    await page.getByRole('button', { name: 'Add to Cart' }).click();
  });

  await test.step('Complete checkout', async () => {
    await page.goto('/checkout');
    await page.getByRole('button', { name: 'Pay Now' }).click();
  });

  await test.step('Verify confirmation', async () => {
    await expect(page.getByRole('heading')).toContainText('Order Confirmed');
  });
});

Key Workflows

Forms & Navigation

// Form submit and wait for navigation (auto-waiting)
await page.getByRole('button', { name: 'Login' }).click();
await expect(page).toHaveURL(/.*dashboard/);

// Form with API response validation
const responsePromise = page.waitForResponse(
  r => r.url().includes('/api/login') && r.status() === 200
);
await page.getByRole('button', { name: 'Login' }).click();
const response = await responsePromise;

API Testing (Request Fixture)

test('API health check', async ({ request }) => {
  const response = await request.get('/api/health');
  expect(response.ok()).toBeTruthy();
  expect(await response.json()).toMatchObject({ status: 'ok' });
});

API Mocking & Interception

test('handles API error', async ({ page }) => {
  await page.route('**/api/users', route =>
    route.fulfill({ status: 500, body: JSON.stringify({ error: 'Server error' }) })
  );
  await page.goto('/users');
  await expect(page.getByRole('alert')).toContainText('Something went wrong');
});

Responsive Testing

const viewports = [
  { width: 375, height: 667, name: 'mobile' },
  { width: 768, height: 1024, name: 'tablet' },
  { width: 1280, height: 720, name: 'desktop' },
];

for (const vp of viewports) {
  test(`navigation works on ${vp.name}`, async ({ page }) => {
    await page.setViewportSize(vp);
    await page.goto('/');
    // Mobile: hamburger menu
    if (vp.width < 768) {
      await page.getByRole('button', { name: /menu/i }).click();
    }
    await page.getByRole('link', { name: 'About' }).click();
    await expect(page).toHaveURL(/about/);
  });
}

Configuration

Use playwright.config.ts for project-wide settings:

import { defineConfig, devices } from '@playwright/test';

export default defineConfig({
  testDir: './tests',
  retries: process.env.CI ? 2 : 0,
  reporter: [['html'], ['junit', { outputFile: 'results.xml' }]],
  use: {
    baseURL: 'http://localhost:3000',
    trace: 'on-first-retry',
    screenshot: 'only-on-failure',
    video: 'retain-on-failure',
  },
  projects: [
    { name: 'chromium', use: devices['Desktop Chrome'] },
    { name: 'mobile', use: devices['Pixel 5'] },
  ],
  webServer: {
    command: 'npm run dev',
    url: 'http://localhost:3000',
    reuseExistingServer: !process.env.CI,
  },
});

Troubleshooting

CLI Quick Reference

References