API Testing: Automated Testing with Jest and Supertest

Why Test APIs?

Testing ensures your API works correctly, handles errors properly, and maintains quality as you add new features.

Writing API Tests

const request = require('supertest');
const app = require('../server');

describe('User API', () => {
  test('GET /api/users - should return all users', async () => {
    const response = await request(app)
      .get('/api/users')
      .expect(200);
    
    expect(Array.isArray(response.body)).toBe(true);
  });

  test('POST /api/users - should create a new user', async () => {
    const response = await request(app)
      .post('/api/users')
      .send({ name: 'Test', email: 'test@example.com' })
      .expect(201);
    
    expect(response.body.name).toBe('Test');
  });
});

Best Practices

• Test all endpoints
• Test success and error cases
• Test edge cases
• Use test databases
• Clean up test data