test-service.js

class WillService {
  constructor (options) {
  	this.willData = options.willData
  }

  getWill (willId) {
    return this.willData.getWill(willId)
  }

  createWill (data) {
  	return this.willData.create(data) // { title: 'my first will', content: '' }
  }
}

function createWillService (options) {
	return new WillService(options)
}


export createWillService

/////////////////////////////////////////////

import createWillService from 'will-service'
const options = {
	willData: {}
}

const WillService = createWillService(options)
app.get('/wills/{id}', WillService.getWill(req.params.id))
app.post('/wills', WillService.createWill(req.body))