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Testing Best Practices

Comprehensive guidelines for testing applications effectively across all platforms.

Overview​

Effective testing ensures quality, reliability, and user satisfaction. This guide covers testing best practices for web, mobile, and API applications.

Purpose: Ensure quality through comprehensive testing
Owner: QA & Development Teams

Core Testing Principles​

Testing Fundamentals​

  1. Test Early: Start testing from day one
  2. Test Often: Continuous testing throughout development
  3. Automate: Automate repetitive tests
  4. Test Realistically: Use real-world scenarios
  5. Document: Record test cases and results
  6. Fix Fast: Address issues immediately

Testing Types​

Unit Testing​

Purpose: Test individual components

Best Practices:

  • Test one thing at a time
  • Keep tests independent
  • Use descriptive names
  • Aim for high coverage (80%+)
  • Mock external dependencies

Example (JavaScript):

describe('User Service', () => {
  test('should create user with valid data', () => {
    const user = createUser({
      email: 'test@example.com',
      name: 'Test User'
    });
    
    expect(user.email).toBe('test@example.com');
    expect(user.name).toBe('Test User');
  });
  
  test('should throw error with invalid email', () => {
    expect(() => {
      createUser({ email: 'invalid', name: 'Test' });
    }).toThrow('Invalid email');
  });
});

Integration Testing​

Purpose: Test component interactions

Best Practices:

  • Test critical paths
  • Use test databases
  • Clean up after tests
  • Test error scenarios
  • Verify data flow

Example:

describe('User API', () => {
  test('should create and retrieve user', async () => {
    // Create user
    const response = await request(app)
      .post('/api/users')
      .send({ email: 'test@example.com', name: 'Test' });
    
    expect(response.status).toBe(201);
    const userId = response.body.id;
    
    // Retrieve user
    const getResponse = await request(app)
      .get(`/api/users/${userId}`);
    
    expect(getResponse.status).toBe(200);
    expect(getResponse.body.email).toBe('test@example.com');
  });
});

End-to-End Testing​

Purpose: Test complete user flows

Best Practices:

  • Test critical user journeys
  • Use realistic data
  • Test on real browsers
  • Include edge cases
  • Maintain test stability

Example (Playwright):

test('user can complete checkout', async ({ page }) => {
  // Login
  await page.goto('/login');
  await page.fill('#email', 'user@example.com');
  await page.fill('#password', 'password');
  await page.click('button[type="submit"]');
  
  // Add to cart
  await page.goto('/products/123');
  await page.click('button:has-text("Add to Cart")');
  
  // Checkout
  await page.goto('/cart');
  await page.click('button:has-text("Checkout")');
  
  // Verify order
  await expect(page.locator('.order-confirmation')).toBeVisible();
});

Web Testing​

Browser Testing​

Test On:

  • Chrome (latest 2 versions)
  • Firefox (latest 2 versions)
  • Safari (latest 2 versions)
  • Edge (latest version)
  • Mobile browsers

Responsive Testing:

  • Desktop (1920×1080, 1366×768)
  • Tablet (768×1024)
  • Mobile (375×667, 414×896)

Accessibility Testing​

Tools:

  • axe DevTools
  • WAVE
  • Lighthouse
  • Screen readers

Checklist:

  • Keyboard navigation
  • Screen reader compatible
  • Color contrast
  • Alt text for images
  • Form labels
  • ARIA attributes

Performance Testing​

Metrics:

  • Page load time < 3s
  • First Contentful Paint < 1.8s
  • Time to Interactive < 3.8s
  • Lighthouse score > 90

Tools:

  • Lighthouse
  • WebPageTest
  • Chrome DevTools

Mobile Testing​

Device Testing​

Test On:

  • iOS (latest 2 versions)
  • Android (latest 3 versions)
  • Various screen sizes
  • Different network conditions

Mobile-Specific Tests​

Test:

  • Touch interactions
  • Gestures
  • Orientation changes
  • Background/foreground
  • Push notifications
  • Offline functionality
  • Battery usage

Tools​

  • XCTest (iOS)
  • Espresso (Android)
  • Appium (Cross-platform)
  • Firebase Test Lab
  • BrowserStack

API Testing​

API Test Cases​

Test:

  • Valid requests
  • Invalid requests
  • Authentication
  • Authorization
  • Rate limiting
  • Error handling
  • Response format

Example:

describe('API Tests', () => {
  test('GET /users returns user list', async () => {
    const response = await api.get('/users');
    
    expect(response.status).toBe(200);
    expect(Array.isArray(response.data)).toBe(true);
  });
  
  test('POST /users requires authentication', async () => {
    const response = await api.post('/users', {
      email: 'test@example.com'
    });
    
    expect(response.status).toBe(401);
  });
  
  test('POST /users validates email', async () => {
    const response = await api
      .post('/users', { email: 'invalid' })
      .set('Authorization', 'Bearer token');
    
    expect(response.status).toBe(400);
    expect(response.body.error).toContain('email');
  });
});

Test Automation​

CI/CD Integration​

Automate:

  • Unit tests on every commit
  • Integration tests on PR
  • E2E tests before deployment
  • Performance tests weekly

Example (GitHub Actions):

name: Tests

on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Install dependencies
        run: npm ci
      - name: Run unit tests
        run: npm test
      - name: Run integration tests
        run: npm run test:integration
      - name: Run E2E tests
        run: npm run test:e2e

Testing Checklist​

Pre-Development​

  • Define test strategy
  • Set up test environment
  • Choose testing tools
  • Write test plan

During Development​

  • Write unit tests
  • Write integration tests
  • Test as you code
  • Review test coverage

Pre-Deployment​

  • Run all tests
  • E2E testing
  • Performance testing
  • Security testing
  • Accessibility testing
  • Browser testing
  • Mobile testing

Post-Deployment​

  • Smoke tests
  • Monitor errors
  • User feedback
  • Analytics review

Best Practices​

General​

Do:

  • ✅ Write tests first (TDD)
  • ✅ Keep tests simple
  • ✅ Test edge cases
  • ✅ Use descriptive names
  • ✅ Maintain tests
  • ✅ Review test failures

Don't:

  • ❌ Skip tests
  • ❌ Test implementation details
  • ❌ Ignore flaky tests
  • ❌ Hard-code test data
  • ❌ Test everything

Test Data​

Best Practices:

  • Use factories/fixtures
  • Clean up after tests
  • Avoid shared state
  • Use realistic data
  • Protect sensitive data

Common Issues​

Issue 1: Flaky Tests​

Causes:

  • Timing issues
  • Shared state
  • External dependencies

Solutions:

  • Add proper waits
  • Isolate tests
  • Mock dependencies
  • Retry logic

Issue 2: Slow Tests​

Causes:

  • Too many E2E tests
  • No parallelization
  • Inefficient tests

Solutions:

  • More unit/integration tests
  • Run tests in parallel
  • Optimize test code
  • Use test doubles

Issue 3: Low Coverage​

Causes:

  • Missing tests
  • Untestable code
  • Legacy code

Solutions:

  • Write missing tests
  • Refactor for testability
  • Gradual coverage increase

Tools & Resources​

Unit Testing:

  • Jest
  • Mocha
  • Jasmine
  • pytest (Python)

E2E Testing:

  • Playwright
  • Cypress
  • Selenium
  • Puppeteer

Mobile Testing:

  • XCTest
  • Espresso
  • Appium
  • Detox

API Testing:

  • Postman
  • REST Client
  • Insomnia
  • Supertest

Last Updated: January 2026
Version: 1.0
Owner: ARUKZ DIGITAL QA Team

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