domain project / e-commerce

E-Commerce

Test strategies for shopping carts, checkout flows, product search, payments, and order management in retail platforms.

Product search & filteringShopping cart & checkoutPayment processingOrder managementInventory & stockUser accounts & wishlists

Domain Overview

E-commerce is the highest-stakes domain for automated testing — a checkout bug directly costs revenue. Testing covers the full purchase funnel: product discovery → cart → checkout → payment → confirmation → order tracking.

Typical stack: Next.js / Nuxt storefront, Stripe / Braintree payments, microservices (cart, inventory, orders, notifications), CDN-delivered product images.

Key Test Areas

Area	What to test	Risk
Product search	Filters, pagination, sorting, empty results	Discovery failure → lost sale
Product detail	Images, variants (size/colour), stock status, add-to-cart	Wrong variant ordered
Cart	Add, remove, quantity update, price calculation, persistence	Price error, lost cart
Checkout	Address form, shipping selection, discount codes	Drop-off, wrong address
Payment	Card validation, 3DS redirect, failure handling	Revenue loss, double charge
Order confirmation	Email trigger, inventory decrement, order record	Fulfilment failure
Account	Registration, login, order history, saved addresses	Data exposure

Test Pyramid for E-Commerce

Unit (60%):   Price calculation, discount logic, tax rules, validation
Integration (30%): Cart API, payment gateway integration, inventory service
E2E (10%):    Critical path: login → search → add to cart → checkout → confirm

Critical E2E tests (must pass before every deploy):

Guest checkout with credit card
Registered user checkout with saved address
Apply discount code, verify price
Out-of-stock product blocks checkout
Payment failure shows error, no order created

Common Failure Scenarios

1. Race condition: two users buy last item simultaneously → oversell
   Test: concurrent checkout API calls, assert only one succeeds

2. Cart total doesn't update after discount → user sees wrong price
   Test: apply coupon, verify cart total, verify order total match

3. 3DS redirect returns to wrong URL → order stuck in pending
   Test: mock 3DS with Stripe test card 4000002500003155

4. Address autocomplete submits before user finishes → wrong delivery
   Test: partial address entry, intercept autocomplete, verify confirmation

5. Inventory not decremented after payment → stock integrity broken
   Test: verify inventory API after successful order

Playwright Patterns for E-Commerce

// Payment with Stripe test cards via page.route()
test('checkout completes with test card', async ({ page }) => {
  await page.goto('/checkout');
  // Fill Stripe Elements iframe
  const stripeFrame = page.frameLocator('iframe[name*="stripe"]').first();
  await stripeFrame.getByPlaceholder('Card number').fill('4242424242424242');
  await stripeFrame.getByPlaceholder('MM / YY').fill('12/28');
  await stripeFrame.getByPlaceholder('CVC').fill('123');
  await page.getByRole('button', { name: 'Place order' }).click();
  await expect(page.getByText('Order confirmed')).toBeVisible();
});

// Cart persistence across sessions
test('cart persists after logout and login', async ({ page, context }) => {
  await page.goto('/products');
  await page.locator('.product-card').first().getByRole('button', { name: 'Add to cart' }).click();

  // Save cookies, new page (simulates new session)
  const cookies = await context.cookies();
  await context.clearCookies();
  await context.addCookies(cookies);

  await page.reload();
  await expect(page.locator('.cart-count')).toHaveText('1');
});