DB test environment initialize

Basic test environment setup

• Create repository
• yarn init -y
• add dependencies and devDependencies

  "devDependencies": {
    "jest": "^22.4.3",
    "nodemon": "^1.17.3"
  },
  "dependencies": {
    "express": "^4.16.3",
    "express-handlebars": "^3.0.0",
    "knex": "^0.14.4",
    "sqlite3": "^4.0.0"
  }

• add scripts into package.json

  "scripts": {
    "start": "nodemon index",
    "test": "jest"
  },

• create a tests folder and create a db.test.js file inside
• write a test case to try if the test environment is ok.

test('test the testing evironment', () => {
  expect(true).toBeTruthy()
})

DB test environment setup

• Create a test-environment.js in tests folder and setup as below

const getDbConn = require('knex')

const testConfig = require('../knexfile').test

module.exports = {
  getTestDb: () => getDbConn(testConfig),
  initialize: (db) => {
    return db.migrate.latest()
      .then(() => {
        return db.seed.run()
      })
  },
  cleanup: (db) => {
    return db.destroy()
  }
}

• Copy seed folder into tests folder

• Add test setup into knexfile.js

  test: {
    client: 'sqlite3',
    connection: {
      filename: ':memory:'
    },
    seeds: {
      directory: './tests/seeds'
    },
    useNullAsDefault: true
  }

• Add below setup into db.test.js

const env = require('./test-environment')
const db = require('../db')

let testDb = null

beforeEach(() => {
  testDb = env.getTestDb()
  return env.initialize(testDb)
})

afterEach(() => {
  return env.cleanup(testDb)
})

Add test cases into db.test.js

• remember to pass testDb into functions you wanna test to replace the knex setup to "test" in knexfile