Unit Testing with Jasmine - Can not spyOn mocked method

Question

I am writing a javascript library that calls a method on another js lib. Most of the time i would create a mock function of the 3rd party library and spy on it. However, it doesn't seem to work.

For example:

mymain.js

export const checkForExternalFunc = () => {
  try {
   return com.externalFunc
  } catch (error) {
    return false
  }
}

mymain_spec.js

import { checkForExternalFunc } from './src';

describe('checkForExternalFunc', () => {
 let com = com || {};
 com.externalFunc = function () {
   return true;
 };

 it('return the function when com.externalFunc is present', () => {
  spyOn(com, "externalFunc");

  let check = checkForExternalFunc();
  expect(check).toBe(jasmine.Any(function));
 });
})

and this would give me an error

ReferenceError: com is not defined

Function in 3rd part library

var com = com || {};
com.externalFunc = function () {
   // return something
};

Any suggestion how i can approach this? Also i have researched a little on Stub with Sinon but not sure how to use it properly. Any help will be appreciated. Thanks!!

Note: I setup project with webpack + babel, karma, jasmine.

Answer 1

Thanks @AdityaBhave for pointing out. I only need to make sure my mock function and the actual one are actually the same. Please see comment above.