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

A functional programming library.

import __ from '../../src/Function/__'
/**
 * (*... -> b) -> (a -> b)
 */
import unary from '../../src/Function/unary'

test('unary(not using __), the original arity is 1', () => {
  expect(
    unary(a => [a])(1)
  ).toEqual([1])
})

test('unary(not using __), the original arities are 2', () => {
  expect(
    unary((a, b) => [a, b])(1)
  ).toEqual([1, undefined])
})

test('unary(using __)', () => {
  expect(
    unary(__)(a => [a])(1)
  ).toEqual([1])
})