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

A functional programming library.

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

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

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