@arrows/array/src/zip_.test.ts

Functional tools for JS arrays

import { zip_ } from "./index"

describe("Array zip", () => {
  it("returns correct pairs for arrays with equal length", () => {
    const arr = [1, 2, 3]
    const otherArr = [3, 4, 5]

    const result = zip_(otherArr, arr)
    const result2 = zip_(otherArr)(arr)

    const expected = [
      [1, 3],
      [2, 4],
      [3, 5],
    ]

    expect(result).toEqual(result2)
    expect(result).toEqual(expected)
  })

  it("returns correct pairs for when base array is shorter", () => {
    const arr = [1, 2]
    const otherArr = [3, 4, 5]

    const result = zip_(otherArr, arr)
    const result2 = zip_(otherArr)(arr)

    const expected = [
      [1, 3],
      [2, 4],
    ]

    expect(result).toEqual(result2)
    expect(result).toEqual(expected)
  })

  it("returns correct pairs for when base array is longer", () => {
    const arr = [1, 2, 3]
    const otherArr = [3, 4]

    const result = zip_(otherArr, arr)
    const result2 = zip_(otherArr)(arr)

    const expected = [
      [1, 3],
      [2, 4],
    ]

    expect(result).toEqual(result2)
    expect(result).toEqual(expected)
  })

  it("always returns a new array", () => {
    const arr = []
    const otherArr = []
    const result = zip_(otherArr)(arr)

    expect(result).not.toBe(arr)
  })
})

describe("Array zip all", () => {
  it("returns correct pairs for arrays with equal length", () => {
    const arr = [1, 2, 3]
    const otherArr = [3, 4, 5]

    const result = zip_.all(otherArr, arr)
    const result2 = zip_.all(otherArr)(arr)

    const expected = [
      [1, 3],
      [2, 4],
      [3, 5],
    ]

    expect(result).toEqual(result2)
    expect(result).toEqual(expected)
  })

  it("returns correct pairs for when base array is shorter", () => {
    const arr = [1, 2]
    const otherArr = [3, 4, 5]

    const result = zip_.all(otherArr, arr)
    const result2 = zip_.all(otherArr)(arr)

    const expected = [
      [1, 3],
      [2, 4],
      [undefined, 5],
    ]

    expect(result).toEqual(result2)
    expect(result).toEqual(expected)
  })

  it("returns correct pairs for when base array is longer", () => {
    const arr = [1, 2, 3]
    const otherArr = [3, 4]

    const result = zip_.all(otherArr, arr)
    const result2 = zip_.all(otherArr)(arr)

    const expected = [
      [1, 3],
      [2, 4],
      [3, undefined],
    ]

    expect(result).toEqual(result2)
    expect(result).toEqual(expected)
  })

  it("always returns a new array", () => {
    const arr = []
    const otherArr = []
    const result = zip_.all(otherArr)(arr)

    expect(result).not.toBe(arr)
  })
})