How to mock a module that exports a factory function with Jest

makeMenusClient.js

import fetch from 'node-fetch';

function makeMenusClient(context) {
  return {
    getMenus: async rid =>
      fetch(`${context.menusBaseUrl}/${rid}`)
        .then(response => response.json())
        .then(json => json)
  };
}

export default makeMenusClient;

makeRestaurantDetails.js

import makeMenusClient from './makeMenusClient';

async function makeRestaurantDetails(context, options) {
  const menusClient = makeMenusClient(context);
  const menus = await menusClient.getMenus(options.rid);

  return {
    menus,
    name: options.name,
    rid: options.rid
  };
}

export default makeRestaurantDetails;

makeRestaurantDetails.test.js

import makeMenusClient from './makeMenusClient';
import makeRestaurantDetails from './makeRestaurantDetails';

jest.mock('./makeMenusClient', () => {
  // check: https://stackoverflow.com/a/51534326/752391
  const mockMenusClient = { getMenus: jest.fn() };
  return jest.fn(() => mockMenusClient);
});

test('makeRestaurantDetails', async () => {
  const context = {
    menusBaseUrl: 'http://menus.opentable.com/api/v1'
  };

  const options = {
    name: 'Urban Remedy',
    rid: 8
  };

  makeMenusClient().getMenus.mockImplementation(() => [
    { title: 'Brunch' },
    { title: 'Dinner' }
  ]);

  expect(await makeRestaurantDetails(context, options)).toMatchSnapshot();
});

makeRestaurantDetails.test.js.snap

// Jest Snapshot v1, https://goo.gl/fbAQLP

exports[`makeRestaurantDetails 1`] = `
Object {
  "menus": Array [
    Object {
      "title": "Brunch",
    },
    Object {
      "title": "Dinner",
    },
  ],
  "name": "Urban Remedy",
  "rid": 8,
}
`;