Extracting common jest mock into util file

Question

I've gone through the official Jest docs around manual mocking but I can't quite make sense of it.

I have a file that exports an object of computed values

utils.js

export const getCalculatedValues = (stuff) => ({
   val1: 'val1',
   val2: 'val2',
   ...
});

I am then using this within several other files that I am attempting to test - For example:

usage.js

import {getCalculatedValues} from './utils';

export const doSomething = () => getCalculatedValues('some-val');

So far, I have managed to mock the original getCalculatedValues

usage.test.js

jest.mock('./utils', () => ({
  __esModule: true,
  getCalculatedValues: {
    val1: 123,
    val2: 321,
    ...
  }
}));


// Assume this passes ;-)
it('Should return mock values', () => {
    const res = doSomething();
    expect(res.val1).toEqual(123);
});

As mentioned previously, I am using getCalculatedValues in several different files which would mean that I am needing to perform the jest.mock of it within each of their test files, which is a lot of duplication.

I am trying to get my head around the "manual mocking" aspect of Jest but I can't seem to understand what I should be doing...

I understand that I should create a file within a __mocks__ directory, but from there, I'm not entirely sure what should go in that file...

Answer 1

Just import the file that you are trying to mock on the global level of the test server.

import utils from "../src/utils.js";