e2e-testing

End-to-End Testing

When to Use

• Validating critical user journeys work from start to finish
• After major refactors that may break integration between components
• Before releases to verify the full system works together
• When unit tests pass but users report bugs in real workflows
• Setting up regression tests for frequently broken features

Prerequisites

• Application can be started in a test/dev environment
• E2E test framework installed (Playwright, Cypress, Selenium, etc.)
• Test data and fixtures available or can be seeded
• Understanding of the most important user workflows

Workflow

1. Identify Critical User Paths

Map the workflows that must always work:

# Find existing E2E tests to understand what's covered
glob pattern="**/*.e2e.*"
glob pattern="**/e2e/**/*.{ts,js}"
glob pattern="**/cypress/**/*.{ts,js}"
glob pattern="**/playwright/**/*.{ts,js}"

Prioritize paths by business impact:

Priority	Path	Example
🔴 P0	Revenue-critical	Signup → Purchase → Confirmation
🔴 P0	Authentication	Login → Access protected resource
🟡 P1	Core features	Create item → Edit → Delete
🟡 P1	Data integrity	Import → Transform → Export
🟢 P2	Secondary flows	Settings → Profile update

2. Set Up the Test Environment

# Start the application in test mode
$env:NODE_ENV="test"
npm run dev  # mode: async, detach: true

# Seed test data
npm run db:seed:test 2>&1

# Verify the app is running
curl -s http://localhost:3000/health

3. Write E2E Tests

Playwright example:

// e2e/auth.spec.ts
import { test, expect } from '@playwright/test';

test.describe('Authentication Flow', () => {
  test('user can sign up and log in', async ({ page }) => {
    // Navigate to signup
    await page.goto('/signup');

    // Fill the form
    await page.fill('[name="email"]', '[email protected]');
    await page.fill('[name="password"]', 'SecurePass123!');
    await page.click('button[type="submit"]');

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

  test('shows error for invalid credentials', async ({ page }) => {
    await page.goto('/login');
    await page.fill('[name="email"]', '[email protected]');
    await page.fill('[name="password"]', 'wrong');
    await page.click('button[type="submit"]');

    await expect(page.locator('.error')).toContainText('Invalid credentials');
    await expect(page).toHaveURL('/login');
  });
});