Using nock and Jasmine to test a helper method

[richlewis14]

Hi

Just come across nock (sorry), so first time using it

Im looking to test the following method but my test fails with Expected spy storeDeviceId to have been called with: [ '1234-5678' ] but it was never called.

I doubt this is a nock issue, more user error with the test, but any assistance would be appreciated

Method to test

async function getDeviceId() {
  const API_URL = `${BASE_URL}/endpoint_url`;

  try {
    const response = await fetch(API_URL);
    if (!response.ok) {
      throw new Error(`HTTP error ${response.status}`);
    }

    const uuid = await response.text();

    if (uuid) {
      await storeDeviceId(uuid);
    } else {
      throw new Error("UUID is not available");
    }
  } catch (error) {
    console.error("Error fetching uuid:", error);
  }
}

Unit test

import { exportedForTesting } from "../src/my_helper.js";
const { storeDeviceId, getDeviceId } = exportedForTesting;
import nock from 'nock';

describe("getDeviceId", () => {
  beforeEach(() => {
    nock.disableNetConnect();
  });

  afterEach(() => {
    nock.cleanAll();
    nock.enableNetConnect();
  });

  it("should call storeDeviceId with a valid UUID when the API call is successful", async () => {
    const mockUuid = '1234-5678';
    nock(BASE_URL)
      .get('/endpoint_url')
      .reply(200, mockUuid);
    
    const storeDeviceIdSpy = spyOn(exportedForTesting, 'storeDeviceId');
    await getDeviceId();

    expect(storeDeviceIdSpy).toHaveBeenCalledWith(mockUuid);
});

Just wondering if anyone had any pointers or let me know what im possibly doing wrong?

Thanks

[mastermatt]

@richlewis14 If you're using the native fetch in newer Node versions or Undici directly (which is what is used for native fetch), then I'm afraid Nock isn't going to work. ref #2183
Nock simply doesn't support it and at this time it doesn't seem like anyone is interested in taking on the massive lift it would take to add support. Full transparency, I'm one of the core maintainers.

[richlewis14]

Hey @mastermatt , thank you for the response. Ive installed node-fetch via npm, not sure if that makes a difference?

I don't appear to have any issues with nock mocking (intercepting) the requests, I get the response im expecting (200, 500, JSON objects returned etc). As a side note, how do I get a ok: false to be returned ?

My issue is I don't appear to be able to spyOn a method that's called after the api mock request has completed (even though functionally I can see that method has done its job, I.e write to localStorage)

Anyway, was just wondering if anyone could spot something I may have missed

No problem if not, thanks for at least replying 😀

[mastermatt]

node-fetch should still work with nock,as it uses the native http/https modules.

I'm not sure what you're asking with "how do I get a ok: false to be returned ?". If the intent is to have the mock response body be JSON ie {"ok": false}, then you can just pass plain objects to the .reply method.

nock(BASE_URL)
      .get('/endpoint_url')
      .reply(200, { ok: false });

As for your real issue with spying on storeDeviceId. This is probably a better question for the Jest community. I'd recommend StackOverflow. My guess is that exportedForTesting isn't exporting/importing the way you want it to so you end up spying on a different instance of storeDeviceId.

[richlewis14]

@mastermatt ok thanks, I'll reach out to that community/Stackoverflow and see what people recommend

My question around ok: false was I my api call I check the response like so

if (response.ok) {
return response.json();
}

So was just wondering how to set that up with nock

[mastermatt]

The response.ok property is based on the response status code.
https://www.npmjs.com/package/node-fetch#responseok

Convenience property representing if the request ended normally. Will evaluate to true if the response status was greater than or equal to 200 but smaller than 300.

So something like this would cause ok to be false.

nock(BASE_URL)
      .get('/endpoint_url')
      .reply(500, 'foo');

[richlewis14]

@mastermatt Thank you for your help, very much appreciated 😀