msw/src/core/utils/internal/is-iterable.test.ts

The industry standard for API mocking in JavaScript.

import { isIterable } from './is-iterable'

test('returns true given an iterator', () => {
  expect(
    isIterable(
      (function* () {
        yield 2
      })(),
    ),
  ).toEqual(true)
})

test('returns false given a regular function', () => {
  expect(
    isIterable(
      (function () {
        return null
      })(),
    ),
  ).toEqual(false)

  expect(isIterable((() => null)())).toEqual(false)
})