test.js

const { spawn } = require('child_process');
const { request } = require('http');

const PORT = process.env.PORT || 5006;

describe('getting started guide', () => {
  let app;

  beforeEach(async () => {
    app = spawn('node', ['index.js']);
    app.stdout.on('data', (data) => console.log(data.toString()));
    // give the server a short time to start up
    return new Promise((resolve) => setTimeout(resolve, 500));
  });

  afterEach(() => {
    if (app) {
      app.stdout.removeAllListeners();
      app.kill('SIGTERM');
    }
  });

  it('should bind to IPv4 and respond to GET /', async () => {
    const response = await get(`http://127.0.0.1:${PORT}`);
    expect(response.statusCode).toBe(200);
    expect(response.body).toMatch('<title>Node.js Getting Started on Heroku</title>');
    expect(response.body).toMatch('Getting Started on Heroku with Node.js');
  });

  it('should bind to IPv6 and respond to GET /', async () => {
    const response = await get(`http://[::1]:${PORT}`);
    expect(response.statusCode).toBe(200);
    expect(response.body).toMatch('<title>Node.js Getting Started on Heroku</title>');
    expect(response.body).toMatch('Getting Started on Heroku with Node.js');
  });
});

async function get(url) {
  return new Promise((resolve, reject) => {
    const req = request(url, { method: 'GET' }, (res) => {
      let body = '';
      res.setEncoding('utf-8');
      res.on('data', (data) => (body += data));
      res.on('end', () => {
        resolve({
          statusCode: res.statusCode,
          body: body,
        });
      });
      res.on('error', reject);
    });
    req.on('error', reject);
    req.end();
  });
}