“Testing with NestJS: A Step-by-Step Guide to End-to-End Testing”

Quality Assurance Strategy in Software Development: End-to-End Testing with NestJS

In software development, a quality assurance strategy is crucial for ensuring the reliability and performance of an application. One key aspect of a QA strategy is testing, which includes unit tests, end-to-end tests, and integration tests. In this article, we will focus on creating end-to-end tests with NestJS, a popular framework for building server-side applications.

What is Test-Driven Development?

Test-driven development (TDD) is a software development process that relies on the repetitive cycle of writing automated tests before writing the actual code. This approach ensures that the code is testable, reliable, and meets the required functionality. TDD involves three simple rules:

1. Write a test for the next bit of functionality.
2. The code must be functional before the test passes.
3. Refactoring is critical to ensure that both old and new code is well-structured.

Benefits of Test-Driven Development

TDD provides several benefits, including:

• Rapid testing, coding, and refactoring.
• Separation of interface from implementation.
• Focus on class behavior rather than implementation.
• Time-saving on debugging.

Creating End-to-End Tests with NestJS

NestJS provides a built-in testing framework that makes it easy to create end-to-end tests. We will use Supertest to simulate requests to our application’s endpoints.

Example: Creating End-to-End Tests for Authentication Controller

Let’s create an example of end-to-end tests for an authentication controller. We will test the registration and login functionality.

“`typescript
// auth.e2e-spec.ts
import { Test } from ‘@nestjs/testing’;
import { AppModule } from ‘./app.module’;
import { NestExpressApplication } from ‘@nestjs/platform-express’;
import { supertest } from ‘supertest’;

describe(‘AuthController’, () => {
let app: NestExpressApplication;
let request;

beforeEach(async () => {
const moduleFixture = await Test.createTestingModule({
imports: [AppModule],
}).compile();

app = moduleFixture.createNestApplication<NestExpressApplication>();
await app.init();
request = supertest(app.getHttpServer());

});

describe(‘POST /auth/register’, () => {
it(‘should register a new user’, async () => {
const mockUser = {
username: ‘test’,
email: ‘[email protected]’,
password: ‘password’,
};

  const response = await request.post('/auth/register').send(mockUser);
  expect(response.status).toBe(201);
  expect(response.body).toHaveProperty('id');
});

});

describe(‘POST /auth/login’, () => {
it(‘should login a user’, async () => {
const mockUser = {
email: ‘[email protected]’,
password: ‘password’,
};

  const response = await request.post('/auth/login').send(mockUser);
  expect(response.status).toBe(200);
  expect(response.body).toHaveProperty('token');
});

});
});
“`

Conclusion

In this article, we have seen how to create end-to-end tests with NestJS using Supertest. End-to-end testing is a crucial part of a quality assurance strategy, and NestJS provides a built-in testing framework that makes it easy to create comprehensive tests for our applications. By following the principles of test-driven development, we can ensure that our code is reliable, testable, and meets the required functionality.