12345678910111213141516
import { nextIndex } from './nextIndex'
const list = [ 1, 2, 3, 4 ]
test('happy path', () => {  expect(nextIndex(2, list)).toEqual(3)})
test('go back to the start', () => {  expect(nextIndex(3, list)).toEqual(0)})
test('current index is too big', () => {  expect(nextIndex(32, list)).toEqual(0)})