Attempting to mock child method, fails if parent module imports it using object destructuring

I was doing some basic jest unit testing in attempt to learn it more.

I have this issue I do not know how to explain

This file has the child function add

// FileB.js 

const add = (a, b) => {
  return a + b;
}

module.exports = {
  add,
};

This file has the parent function addTen

// FileA.js

const { add } = require('./FileB');

const addTen = num => {
  return add(10, num);
}

module.exports = {
  addTen,
};

this is my test file, where I am trying to either check <mockedFunction/spy>.mock.calls or do toHaveBeenCalledWith to see if the inner child method, add, is being passed in 10,10 when i call addTen(10);

This file is not used in any real env, its simply me trying to learn jest + unit testing more.

// randomTest.js

const { addTen } = require('../src/FileA');
const fileB = require('../src/FileB'); 

describe('temp', () => {
  it('temp', () => {
    const addSpy = jest.spyOn(fileB, 'add');

    addTen(10);
    console.log(addSpy.mock.calls);

    expect(addSpy).toHaveBeenCalledWith(10,10)
  });
});

Now for the issue, the test fails, saying add was never called, or nothing passed in. I logged the add function within FileB

However, if I modify FileA in this way, by importing entore module instead of destructuring, the test passes and I cna log out the functions and everything and see it works

This is what works

// FileA.js

const fileB = require('./FileB');

const addTen = num => {
  return fileB.add(10, num);
}

module.exports = {
  addTen,
};

Why does this slight change work? And is there a way to avoid this and keep my destrcutoring?

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