moy-fp/test/List/adjust.test.js

A functional programming library.

import __ from '../../src/Function/__'
/**
 * Number -> (a -> a) -> [a] -> [a]
 */
import adjust from '../../src/List/adjust'

test('adjust(not using __), positive number', () => {
  expect(
    adjust(1)(x => x + 1)([1, 2, 3, 4])
  ).toEqual([1, 3, 3, 4])
})

test('adjust(not using __), negative number', () => {
  expect(
    adjust(-2)(x => x + 1)([1, 2, 3, 4])
  ).toEqual([1, 2, 4, 4])
})

test('adjust(using __), positive number', () => {
  expect(
    adjust(1, __, [1, 2, 3, 4])(x => x + 1)
  ).toEqual([1, 3, 3, 4])
})