Un buen flujo de trabajo en Node.js: tests con Jest

package.json

{
  "name": "jest",
  "version": "1.0.0",
  "main": "sum.js",
  "repository": "git@gist.github.com:87a5d1b26cf2becc5d826d224c5b13f0.git",
  "author": "EdgarJRG <edgarj_rodriguezg@hotmail.com>",
  "license": "MIT",
  "scripts": {
    "test": "jest"
  },
  "dependencies": {
    "jest": "^23.4.2"
  }
}

sum.js

module.exports.sum = function (a, b) {
  return a + b;
}

sum.test.js

const { sum } = require('./sum');

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});