conductor/__tests__/curryN.js

A modern & functional JavaScript utility library

const curryN = require('../src/curryN')
const add = curryN(3, (a, b, c) => a + b + c)

describe('curry', () => {
  it('should curry the input function', () => {
    expect(add(1, 2, 3)).toBe(6)
    expect(add(1)(2)(3)).toBe(6)
    expect(add(1, 2)(3)).toBe(6)
    expect(add(1)(2, 3)).toBe(6)
  })

  it('should preserve the function\'s arity', () => {
    expect(add.length).toBe(3)
    expect(add(1).length).toBe(2)
    expect(add(1, 2).length).toBe(1)
    expect(add(1)(2).length).toBe(1)
    expect(add(1)(2).length).toBe(1)
  })

  it('should accept as many arguments as the provided arity', () => {
    expect(curryN(3, (a, b) => a + b)(1, 2)).toBeInstanceOf(Function)
    expect(curryN(3, (a, b) => a + b)(1, 2, 3)).toBe(3)
    // eslint-disable-next-line no-unused-vars
    expect(curryN(2, (a, b, c) => a + b + 3)(1, 2)).toBe(6)
  })
})