conductor/__tests__/reduceSync.js

A modern & functional JavaScript utility library

const reduceSync = require('../src/reduce')

const array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const object = {
  firstname: 'James',
  lastname: 'M',
}
const map = new Map([['firstname', 'James'], ['lastname', 'M']])
const set = new Set(array)

describe('reduceSync', () => {
  it('should reduce an array into a new array containing the same elements', () => {
    const reducedArray = reduceSync((acc, item) => acc.concat(item), [], array)
    expect(reducedArray).toEqual(array)
    expect(reducedArray).not.toBe(array)
  })

  it('should reduce an object into a new object containing the same elements', () => {
    const newObject = reduceSync(
      (acc, value, key) => {
        acc[key] = value
        return acc
      },
      {},
      object
    )
    expect(newObject).toEqual(object)
    expect(newObject).not.toBe(object)
  })

  it('should reduce a map into a new map containing the same elements', () => {
    const newMap = reduceSync(
      (acc, value, key) => {
        acc.set(key, value)
        return acc
      },
      new Map(),
      map
    )
    expect(newMap).toEqual(map)
    expect(newMap).not.toBe(map)
  })

  it('should reduce a set into a new set containing the same elements', () => {
    const newSet = reduceSync(
      (acc, value) => {
        acc.add(value)
        return acc
      },
      new Set(),
      set
    )
    expect(newSet).toEqual(set)
    expect(newSet).not.toBe(set)
  })
})