Mock Node External Module Default With Chained Method Using Jest

In our node CLI we have a simple method: 'use strict'; const ora = require('ora'); module.exports = function startSpinner({ textOnStart, color, spinnerType }) { const spinner =

Solution 1:

You've got a couple of options:

---

You can mock ora like this:

jest.mock('ora', () => {
  const start = jest.fn();
  const result = { start };
  return jest.fn(() => result);
});

...and then call ora to get the object it returns (since it always returns the same object) and use that object to access start:

it('should call ora start', () => {
  const result = ora();
  expect(result.start).toHaveBeenCalled();  // Success!
});

---

Or if you want you can attach the start mock as a property to the ora mock as an easy way to access it during your tests like this:

const ora = require('ora');

jest.mock('ora', () => {
  const start = jest.fn();
  const result = { start };
  const ora = jest.fn(() => result);
  ora.start = start;  // attach the start mock to orareturn ora;
});

const startSpinner = require('./startSpinner');

describe('startSpinner', () => {
  beforeEach(() => {
    startSpinner({});
  });

  describe('ora', () => {
    it('should call ora', () => {
      expect(ora).toHaveBeenCalled();  // Success!
    });

    it('should call ora start', () => {
      expect(ora.start).toHaveBeenCalled();  // Success!
    });
  });
});