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

A functional programming library.

import __ from '../../src/Function/__'
/**
 * Functor f => f (f a) -> f a
 */
import join from '../../src/Functor/join'
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('join(not using __), array', () => {
  expect(
    join([[1, 2], [3, 4]])
  ).toEqual([1, 2, 3, 4])
})

test('join(not using __), identity', () => {
  expect(
    inspect(join(Identity.of(Identity.of(12))))
  ).toBe('Identity(12)')
})

test('join(using __), array', () => {
  expect(
    join(__)([[1, 2], [3, 4]])
  ).toEqual([1, 2, 3, 4])
})