moy-fp/test/Functor/map.test.js

A functional programming library.

import __ from '../../src/Function/__'
/**
 * Functor f => (a -> b) -> f a -> f b
 */
import map from '../../src/Functor/map'
import Identity from '../../src/Functor/Identity/index'

/**
 * you should not use this similar funciton to get value anywhere in your application
 * if you must need the inner value, you may need Comonad
 * here is just simple for test
 */
const inspect = x => `Identity(${x.value})`

test('map(not using __), array', () => {
  expect(
    map(x => x + 1)([1, 2, 3, 4])
  ).toEqual([2, 3, 4, 5])
})

test('map(not using __), identity', () => {
  expect(
    inspect(map(x => x + 1)(Identity.of(12)))
  ).toBe('Identity(13)')
})