moy-fp/test/Relation/maxBy.test.js

A functional programming library.

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

test('maxBy(not using __), return first', () => {
  expect(
    maxBy(x => x.id)({id: 2})({id: 1})
  ).toEqual({id: 2})
})

test('maxBy(not using __), return second', () => {
  expect(
    maxBy(x => x.id)({id: 1})({id: 2})
  ).toEqual({id: 2})
})

test('maxBy(using __), return first', () => {
  expect(
    maxBy(x => x.id, __, {id: 1})({id: 2})
  ).toEqual({id: 2})
})