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

A functional programming library.

import __ from '../../src/Function/__'
/**
 * (*... -> c) -> ((a, b) -> c)
 */
import binary from '../../src/Function/binary'

test('binary(not using __), original arity is 1', () => {
  expect(
    binary(x => [x, x + 1])(1)(2)
  ).toEqual([1, 2])
})

test('binary(not using __), original arities are 3', () => {
  expect(
    binary((x, y, z) => [x, y, z])(1)(2)
  ).toEqual([1, 2, undefined])
})

test('binary(using __), original arity is 1', () => {
  expect(
    binary(x => [x, x + 1])(__, 2)(1)
  ).toEqual([1, 2])
})