Test Automation

Test Automation Strategies

Pyramid Approach

• Unit Tests (70%): Fast, isolated tests for individual functions and methods
• Integration Tests (20%): Tests that verify components work together
• End-to-End Tests (10%): Tests that simulate real user flows through the application

Risk-Based Testing

• Prioritize automation based on business risk and frequency of use
• Focus on critical paths and high-value features first
• Automate regression tests to prevent regressions

Test Data Management

• Fixtures: Pre-defined test data sets for consistent test runs
• Factories: Dynamic test data generation for flexibility
• Test Builders: Fluent APIs for creating complex test objects
• Data Seeding: Database seeding for integration and E2E tests

Test Design Patterns

Page Object Model (POM)

• Encapsulate page elements and interactions in page objects
• Separate test logic from page interaction logic
• Improve test maintainability and reusability
• Example structure:

  class LoginPage {
    constructor(page) {
      this.page = page;
      this.usernameInput = page.locator('#username');
      this.passwordInput = page.locator('#password');
      this.loginButton = page.locator('#login');
    }
    
    async login(username, password) {
      await this.usernameInput.fill(username);
      await this.passwordInput.fill(password);
      await this.loginButton.click();
    }
  }
  

Screenplay Pattern

• Actor-based testing with human-like interactions
• Composable abilities and tasks
• More readable and maintainable test scenarios
• Example structure:

  actor.attemptsTo(
    Navigate.to('/login'),
    Enter.theValue('username').into('#username'),
    Enter.theValue('password').into('#password'),
    Click.on('#login')
  );
  

Data-Driven Testing

• Separate test logic from test data
• Run same test with multiple data sets
• Use CSV, JSON, or database for test data
• Example structure:

  const testData = [
    { username: 'user1', password: 'pass1', expected: 'success' },
    { username: 'user2', password: 'pass2', expected: 'success' },
    { username: 'invalid', password: 'wrong', expected: 'failure' }
  ];
  
  testData.forEach(({ username, password, expected }) => {
    test(`login with ${username}`, async ({ page }) => {
      await login(page, username, password);
      await expect(page.locator('.status')).toHaveText(expected);
    });
  });
  

Mocking and Stubbing Techniques

When to Mock

• External API calls
• Database operations
• File system operations
• Time-dependent code
• Random number generation

Mocking Best Practices

• Mock at boundaries, not within the system under test
• Keep mocks simple and realistic
• Verify mock interactions when necessary
• Use test doubles appropriately (stub, mock, spy, fake)

Example Mocking (Jest)

jest.mock('./api');
import { fetchUser } from './api';

test('fetches user data', async () => {
  fetchUser.mockResolvedValue({ id: 1, name: 'Test User' });
  
  const result = await getUser(1);
  expect(result).toEqual({ id: 1, name: 'Test User' });
  expect(fetchUser).toHaveBeenCalledWith(1);
});

Test Isolation

Preventing Test Interference

• Use fresh test data for each test
• Clean up after each test (teardown)
• Avoid shared state between tests
• Use test databases or transactions

Database Isolation

• Wrap tests in database transactions and rollback
• Use in-memory databases for faster tests
• Seed test data before each test
• Clean up test data after each test

Flaky Test Prevention

Common Causes

• Race conditions and timing issues
• Dependency on external services
• Non-deterministic test data
• Browser state pollution
• Parallel test execution conflicts

Prevention Strategies

• Use explicit waits instead of implicit waits
• Mock external dependencies
• Use deterministic test data
• Clear browser state between tests
• Configure tests to run sequentially when needed
• Retry flaky tests with proper investigation

Test Reporting and Visualization

Reporting Tools

• Allure: Comprehensive test reporting with history and trends
• Mochawesome: HTML reports for Mocha tests
• Jest HTML Reporters: Visual reports for Jest test suites
• JUnit XML: Standard format for CI/CD integration

Key Metrics to Track

• Test execution time
• Pass/fail rates
• Flaky test rate
• Coverage trends
• Test failure patterns

Dashboard Elements

• Overall test health
• Coverage metrics
• Test execution trends
• Flaky test alerts
• Failure analysis by category