Testing Strategies Overview

Testing Pyramid

        /\
       /UI\          (Few)
      /----\
     / Integ\
    /--------\
   / Unit     \    (Many)
  /___________\

A good test suite has many unit tests, fewer integration tests, and even fewer UI tests.

Unit Tests

Test individual functions or methods in isolation.

test('add(2, 3) returns 5', () => {
  expect(add(2, 3)).toBe(5);
});

Pros: Fast, easy to write, good feedback Cons: Don't test integration

Integration Tests

Test interactions between components or services.

test('user creation with database', async () => {
  const user = await createUser({ email: 'test@example.com' });
  expect(user.id).toBeDefined();
});

End-to-End (E2E) Tests

Test complete user workflows through the UI.

test('user can login and view dashboard', async () => {
  await page.goto('/login');
  await page.fill('input[name="email"]', 'user@example.com');
  await page.click('button[type="submit"]');
  await expect(page).toHaveURL('/dashboard');
});

Other Testing Types

Performance Testing

Ensure application meets performance requirements.

Security Testing

Identify vulnerabilities (penetration testing, static analysis).

Load Testing

Test system under high traffic.

User Acceptance Testing (UAT)

Stakeholders verify requirements met.

Testing Best Practices

• Test behavior, not implementation
• Keep tests independent
• Use descriptive test names
• Aim for high coverage, but not 100%
• Test edge cases and error scenarios
• Mock external dependencies
• Run tests frequently (CI/CD)
• Maintain tests like production code

Test Naming

// Good
test('should return error when email is invalid', () => {});

// Bad
test('test1', () => {});

Coverage Goals

• Unit tests: 80%+ coverage
• Integration tests: Critical paths
• E2E tests: Main user flows

Remember: Coverage is a tool, not a goal.