moy-fp/test/Object/lensPath.test.js

A functional programming library.

import __ from '../../src/Function/__'
import Identity from '../../src/Functor/Identity/index'
/**
 * [k] -> Lens s a
 * Lens s a = Functor f => (a -> f a) -> s -> f s 
 */
import lensPath from '../../src/Object/lensPath'

/**
 * 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(${JSON.stringify(x.value)})`

test('lensPath(not using __), not execute', () => {
  expect(
    lensPath(['a', 'x'])
  ).toEqual(expect.any(Function))
})

test('lensPath(not using __), execute', () => {
  expect(
    inspect(lensPath(['a', 'x'])(Identity)({a: {x: 1}}))
  ).toEqual('Identity({"a":{"x":1}})')
})

test('lensPath(using __), not execute', () => {
  expect(
    lensPath(__)(['a', 'x'])
  ).toEqual(expect.any(Function))
})