Mock promisified AWS service operation calls

sreda.test.js

/* eslint-env jest */
'use strict'

const { read, keys } = require('../sreda')
const AWS = require('aws-sdk')
let ssm = new AWS.SSM()

var ssmPromise = {
  promise: jest.fn().mockImplementation((request) => {
    return new Promise((resolve, reject) => {
      const response = {
        Parameters: [
          {
            Name: 'bar',
            Type: 'String',
            Value: 'barfoorista',
            Version: 1,
            LastModifiedDate: '2018-08-22T13:49:55.717Z',
            ARN: 'arn:aws:ssm:eu-west-1:whatever:parameter/bar'
          },
          {
            Name: 'foo',
            Type: 'String',
            Value: 'foobarista',
            Version: 1,
            LastModifiedDate: '2018-08-22T13:49:41.486Z',
            ARN: 'arn:aws:ssm:eu-west-1:whatever:parameter/foo'
          }
        ],
        InvalidParameters: []
      }
      resolve(response)
    })
  })
}
ssm = { getParameters: () => { return ssmPromise } }

describe('mock AWS.SSM()', () => {
  beforeAll(async () => {
    process.env.NODE_ENV = 'production'
  })

  it(`throws an error if no keys are providerd`, async () => {
    function throwsErr () {
      read(ssm, [])
    }
    expect(throwsErr).toThrowError(`You need to provide a non-empty array of config keys`)
  })

  it(`throws an error if some keys are missing`, async () => {
    expect(keys(ssm, ['foobar'])).rejects.toEqual(new Error(`Missing SSM Parameter Store keys: foobar`))
  })

  it(`throws an error when ssm is throwing one`, async () => {
    ssm = {
      getParameters: () => {
        return {
          promise: jest.fn().mockImplementation((request) => {
            return new Promise((resolve, reject) => {
              return reject(new Error('foobar'))
            }).catch(() => console.log('Ok'))
          })
        }
      }
    }
    expect(keys(ssm, ['foo'])).rejects.toEqual(new Error(`TypeError: Cannot destructure property \`Parameters\` of 'undefined' or 'null'.`))
  })
})