Must extract functions in module to use spy/stub/mock with sinon.js

Question

Saying I have this file index.js :

export const f = () => 5;
export const g = () => f();

And my index-spec.js :

import * as F from './index'
const spy = sinon.spy(F, 'f')
F.g()
assert(F.f.calledOnce)

This code will not work, but I don't understand the reason. If I extract f in another module the code will work.

Can somebody save me! :) Thanks

Answer 1

Your code is not invoking function f. Change Fg() to Ff()