Stubbing non-exported function with sinon

Question

I write a unit-test for doB function of my module.

I want to stub the function doA without exporting it, I prefer not change the way doB accesses doA.

I understand that it cannot be simply stubed because it isnt in the exported object.

How do I stub doA (sinon or any other tool?)

function doA (value) {
   /* do stuff */
}

function doB (value) {
  let resultA = doA(value);
  if (resultA === 'something') {
     /* do some */
  } else {
     /* do otherwise */
  }
}

module.exports = exports = {
   doB
}

mikey · Answer 1 · 2020-07-10T05:49:57.687

3

I did it using rewire too. This is what I came up with

const demographic = rewire('./demographic')

const getDemographicsObject = { getDemographics: demographic.__get__('getDemographics') };

const stubGetDemographics = sinon
 .stub(getDemographicsObject, 'getDemographics')
 .returns(testScores);

demographic.__set__('getDemographics', stubGetDemographics);

Hope this helps

edited Jul 10 '20 at 05:49

answered Jan 21 '19 at 00:43

mikey

1,339
5
22
43

it says _get_ is not a function do we have to have any specific js version in order to use this function? – Taher Ghulam Mohammed Mar 30 '20 at 18:41
Are you using rewire to import the module? did you check examples here: https://github.com/jhnns/rewire ? – mikey Apr 02 '20 at 02:46
1

yes it is working now i was doing it wrong. Thanks for the help – Taher Ghulam Mohammed Apr 02 '20 at 19:18
1

In the snippet, I think `reqire` should be `rewire` – benevolentprof Jul 10 '20 at 00:59

score 1 · Answer 2 · answered Jan 18 '17 at 21:42

1

I've ended up using rewire, I can either just __get__ an internal function from the module and the stub it with sinon or userewire's __with__ utility to invoke a function with replaced internal values

answered Jan 18 '17 at 21:42

agoldis

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16
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hi I am trying the same approach.. with not much luck, are you able to share a snippet of what you have done? – mikey Dec 20 '18 at 23:39
@mikey I afraid I don't have access to the code anymore :( – agoldis Jan 02 '19 at 18:35
all good! I made it somehow, maybe I'll post my answer here!! thank you anyway @agoldis – mikey Jan 08 '19 at 21:13
@mikey, can you please share stub of non-exported function? – Nazeer_hanne Jan 16 '19 at 07:16

score 1 · Answer 3 · answered Sep 08 '20 at 12:53

Actually, if you don't care about fetching the original function, but rather just want to stub it, the first part is unnecessary. You can do something like this instead:

function stubPrivateMethod(modulePath, methodName) {
    const module = rewire(modulePath);
    
    const stub = sinon.stub();

    module.__set__(methodName, stub);

    return stub;
}

Stubbing non-exported function with sinon

3 Answers3