codex-lv4-may-2025

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Level 32: Test the Hello Express Route

Set up Vitest and Supertest to test your Express routes. Start with a simple test for your root route that serves HTML.

Setup:

1. Install testing dependencies: npm install -D vitest supertest @vitest/coverage-v8
2. Create a tests directory in the root of your project.
3. Make sure you’ve completed Level 31: Your Express app should already be exported from src/app.js (if you haven’t done the refactor yet, go back to Level 31 first)

Show Me: basic test setup and Hello Express test

// tests/routes/app.test.js
import { describe, it, expect } from 'vitest';
import request from 'supertest';
import app from '../../src/app.js';

describe('Server Routes', () => {
  it('serves HTML from root route', async () => {
    const res = await request(app).get('/');
    expect(res.status).toBe(200);
    expect(res.text).toContain('<h1>Hello Express!</h1>');
    expect(res.headers['content-type']).toMatch(/html/);
  });
});

Notes:

• No listen() needed: Supertest can work directly with your Express app—you don’t need to call app.listen(). Supertest handles the server setup internally when you pass the app directly to request().
• await is required: Supertest returns a Promise, so you need await when using async/await syntax to get the response object. Without await, res would be a Promise instead of the response, and your assertions wouldn’t work.