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

A functional programming library.

import __ from '../../src/Function/__'
/**
 *  ((a, b) -> Boolean) -> ((a, b) -> Number)
 */
import comparator from '../../src/Function/comparator'

test('comparator(not using __), ascending order', () => {
  expect(
    comparator((a, b) => a < b)(1)(2)
  ).toBe(-1)
})

test('comparator(not using __), descending order', () => {
  expect(
    comparator((a, b) => a > b)(1)(2)
  ).toBe(1)
})

test('comparator(not using __), descending order', () => {
  expect(
    comparator((a, b) => a < b)(1)(1)
  ).toBe(0)
})

test('comparator(using __), ascending order', () => {
  expect(
    comparator((a, b) => a < b)(__, 2)(1)
  ).toBe(-1)
})