failing example of restoring a manual mock

jest-manual-mock-restore.js

'use strict';

let neatCsv = require('neat-csv');
let { parseResponseToJson } = require('./neat-csv.js');

jest.mock('neat-csv', () =>
  jest.fn().mockRejectedValueOnce(new Error('Error while parsing'))
);

const csv = 'type;part\nunicorn;horn\nrainbow;pink';
const apiResponse = {
  body: csv
};

const rejectionOf = (promise) =>
  promise.then(
    (value) => {
      throw value;
    },
    (reason) => reason
  );

test('mocked version', async () => {
  const e = await rejectionOf(parseResponseToJson(apiResponse));
  expect(e.message).toEqual('Error while parsing');
  expect(neatCsv).toHaveBeenCalledTimes(1);
});

test('non mocked version', async () => {
  jest.resetModules();
  neatCsv = require('neat-csv');
  ({ parseResponseToJson } = require('./neat-csv.js'));

  const result = await parseResponseToJson(apiResponse);
  expect(JSON.stringify(result)).toEqual(
    '[{"type":"unicorn","part":"horn"},{"type":"rainbow","part":"pink"}]'
  );
});