npm i cors

const baseVersionSchema = new mongoose.Schema({
  service_name: String,
  service_version: String,
  env: String
})

const baseVersion = new BaseVersionModel({
  service_name: req.body.service_name,
  service_version: buildVersion,
  env: req.body.env
})

npm i --save-dev jest supertest
npm i --save-dev eslint-plugin-jest

// in package.json add this section
"jest": {
    "testEnvironment": "node"
  }

// in .eslintrc.js, add plugins:
'plugin:jest/recommended'

const app = require('../src/app')
const request = require('supertest')

it('should return hello world', async function() {
  const response = await request(app).get('/hello-world')
  expect(response.text).toEqual('hello world')
})

npm install mongodb-memory-server --save-dev

const { MongoMemoryServer } = require('mongodb-memory-server')
const app = require('../../src/app')
const request = require('supertest')
const mongoose = require('mongoose')

let mongod

beforeEach(async () => {
  mongod = new MongoMemoryServer()
  const uri = await mongod.getConnectionString()
  await mongoose.connect(uri)
})

afterEach(async () => {
  mongod.stop()
})

npm install nock --save-dev

nock('https://www.egencia.com')
  .get('/flight-service/base/version')
  .reply(200, {
    application_name: 'flight-service',
    active_profiles: 'prod,prodch,ancillaries,oms',
    stage: 'prod',
    machine_name: 'chexjvgect004',
    application_data: {
      step_bom_version: '8.6.2',
    },
    build_version: '2019-05-27-15-15-94093f32a',
    build_number: '94093f32a449b31104c7c2767ee5fd2a42447b99',
    build_date: '2019-05-27T15:17:025Z',
  })
  .persist()

import axios from 'axios'
export default {
  from(url) {
    return {
      get: ({ name }) => axios.get(`${url}/${name}`),
      list: () => axios.get(url),
      add: body => axios.post(url, body),
      delete: ({ name }) => axios.delete(`${url}/${name}`),
    }
  },
}

  constructor(props) {
    super(props)
    this.state = {
      inputValue: '',
      services: [],
    }
    this.addService = this.addService.bind(this)
  }

  componentDidMount() {
    this.fetchServices(this.props.env)
  }

  async fetchServices(env) {
    const { data } = await api.from(`http://localhost:3000/services/${env}`).list()

    this.setState({ services: data})
  }

  async addService(serviceName) {
    await api.from(`http://localhost:3000/services/`).add({
      service_name: serviceName,
      env: this.props.env
    })
    this.fetchServices(this.props.env)
  }

npm i --save-dev @testing-library/react
npm i --save-dev @testing-library/jest-dom

##also if you do not have jest already 
# npm i --save-dev jest

  "scripts": {
    "start": "parcel index.html --open",
    "build": "parcel build index.html",
    "test": "jest --watchAll"
  }

import React from 'react'
import { render, fireEvent, cleanup } from '@testing-library/react'
import AddService from '../components/AddService'

afterEach(cleanup)

test('create a new service', () => {
  //given
  const handleSubmit = jest.fn()
  const { getByPlaceholderText, getByText } = render(
    <AddService addService={handleSubmit} />,
  )
  getByPlaceholderText(/new/i).value = 'new-service'

  //when
  fireEvent.click(getByText(/Add/i))

  //then
  expect(handleSubmit).toHaveBeenCalledTimes(1)
})