moy-fp/test/Function/descend.test.js

A functional programming library.

import __ from '../../src/Function/__'
/**
 * Ord b => (a -> b) -> a -> a -> Number
 */
import descend from '../../src/Function/descend'

test('descend(not using __), ascending original order', () => {
  expect(
    descend(obj => obj.age, {
      name: 'murakami',
      age: 24,
    }, {
      name: 'yamasita',
      age: 32,
    })
  ).toBe(1)
})

test('descend(not using __), descending original order', () => {
  expect(
    descend(obj => obj.age, {
      name: 'yamasita',
      age: 32,
    },  {
      name: 'murakami',
      age: 24,
    })
  ).toBe(-1)
})

test('descend(not using __), same original order', () => {
  expect(
    descend(obj => obj.age, {
      name: 'yamasita',
      age: 24,
    },  {
      name: 'murakami',
      age: 24,
    })
  ).toBe(0)
})

test('descend(using __), ascending original order', () => {
  expect(
    descend(obj => obj.age, __, {
      name: 'yamasita',
      age: 32,
    })({
      name: 'murakami',
      age: 24,
    })
  ).toBe(1)
})