Test React hook which uses another hook

useExternal.spec.ts

import {useExternal} from "./useExternal";

const useInternal = jest.spyOn(require('./useInternal'), 'useInternal')
useInternal.mockReturnValue(2)

test('useExternal', ()=>{
  const actual = useExternal()
  const expected = 4
  expect(actual).toBe(expected)
})

useExternal.ts

import {useInternal} from "./useInternal";

export const useExternal = ()=>{
  const number = useInternal()
  return number *2
}

useInternal.ts

export const useInternal = ()=>{
  return -1
}