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

Functional tools for JS arrays

import { butLast_ } from "./index"

describe("Array butLast_", () => {
  it("returns the array without last element", () => {
    const arr = [1, 2, 3, 4]

    const result = butLast_(arr)
    const expected = [1, 2, 3]

    expect(result).toEqual(expected)
  })

  it("returns empty array if there is less than two elements", () => {
    const arr = []

    const result = butLast_(arr)
    const expected = []

    expect(result).toEqual(expected)
  })

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

    const result = butLast_(arr)

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