reedx/src/utils/__tests__/createReducer.js

Like redux but with less code

import { isFunction } from 'lodash'
import createReducer from '../createReducer'
import createTypes from '../createTypes'

const name = 'counter'
const state = 0

const increment = (state) => state + 1
const decrement = (state) => state - 1
const handlers = { increment, decrement }

const types = createTypes(name, handlers)
const reducer = createReducer(state, types, handlers)

test('returns a function', () => {
  expect(isFunction(reducer)).toBeTruthy()
})

test('return the initial state', () => {
  expect(reducer(state, {})).toBe(0)
})

test('handler actions on a state', () => {
  const [INCREMENT, DECREMENT] = types

  expect(reducer(state, { type: INCREMENT })).toBe(1)
  expect(reducer(state, { type: DECREMENT })).toBe(-1)
})