getters.js

// store.js
const state = {
  first: "",
  last: ""
}

export const getters = {
  message: (state) => {
    return state.first + ' ' + state.last
  } 
}

// test
import { getters } from './store'

describe('message getter', () => {
  it('returns hello world', () => {
    const state = { first: 'hello', last: 'world' }
    const actual = getters.message(state)
    expect(actual).toBe('hello world')
  })
})