NodeJS : Trouble with ES6, import and export

Question

I'm quite new in the NodeJS world. I have a question : I'm trying to put a unit test with Jest in order to test this 'Service' with the 2 functions as below in the quotationService.js file :

export default ({ quotationRepository }) => {
  const getQuotations = (runComputationData) =>
    Promise.resolve()
      .then(async () => {
        const promise = quotationRepository.runComputation(runComputationData);
        const quotationsResult = await Promise.all([promise]);
        const quotations = quotationsResult[0];

        return quotations;
      })
      .catch((error) => {
        throw error;
      });

      const sum = (a, b) => a + b;

  return {
    getQuotations,
    sum
  };
};

And in my test file, i have :

import quotationServices from '../../../../../src/domain/financing/quotation/quotationServices.js';

describe('sum module', () => {
  test('adds 1 + 2 to equal 3', () => {
    expect(quotationServices.sum(1, 2)).toBe(3);
  });
});

The point is that i don't really know the syntaxe to mock the sum function for a unit test, i have this result :

Does someone have an idea please ? Thanks