JustinDFuller

import orm from 'my_favorite_database_library'

export const models = {
  user: orm.define({
    id: orm.PRIMARY_KEY,
    email: orm.STRING(255)
  })
}

JustinDFuller

import { models } from './models'

export const controllers = {
  user: {
    get({ email }) {
      return models.user.get({
        where: {
          email
        },
        limit: 1

JustinDFuller

import { controllers } from './controllers'

export const routes = {
  user: {
    async get(request, response) {
      response.json(await controllers.user.get(request.query))
    }
  }
}

JustinDFuller

import express from 'express'

import { routes } from './routes'

const server = express()

/**
 * Implement routes
 *
 * server.get('/user', routes.user.get)

JustinDFuller

// not extensible

function getUser() {
  return {
    name: 'Justin',
    email: 'justinfuller@email.com'
  }
}

// Extensible

JustinDFuller

/* json.js */

export default function ({ readFileAsync, writeFileAsync }) {
  return {
    readJsonFile(fileName) {
      return readFileAsync(`${fileName}.json`).then(JSON.parse) 
    },
    writeJsonFile(filePath, fileContent) {
      return writeFileAsync(filePath, JSON.stringify(fileContent)) 
    }

JustinDFuller

interface ComponentLifecycle {
        constructor(props: Object);
        componentDidMount?(): void;
        shouldComponentUpdate?(nextProps: Object, nextState: Object, nextContext: any): boolean;
        componentWillUnmount?(): void;
        componentDidCatch?(error: Error, errorInfo: ErrorInfo): void;
        setState(
            state: ((prevState: Object, props: Object) => Object,
            callback?: () => void
        ): void;

JustinDFuller

/* This is my file I'll be testing foo.js */

export default function ({ readFileAsync }) {
  return {
    readJsonFile (filePath) {
     return readFileAsync(filePath).then(JSON.parse)
    }
  }
}

JustinDFuller

/* This is my file I'll be testing foo.js */

import fs from 'fs'
import { promisify } from 'util'

const readFileAsync = promisify(fs.readFile)

export function readJsonFile (filePath) {
 return readFileAsync(filePath).then(JSON.parse)
}

JustinDFuller

/**
 * Normally you might do:
 * import fs from 'fs-extra-promise'
 * but here we will allow the user of this file to provide the fs module
 */
export default function ({ fs }) {
  return function(fileName) {
    return fs.readFileAsync(fileName, 'utf8') 
  }
}