How to test `functions.https.onCall` firebase cloud functions locally?

Question

I can't seem to find the solution for this in the Firebase Documentation.

I want to test my functions.https.onCall functions locally. Is it possible using the shell or somehow connect my client (firebase SDK enabled) to the local server?

I want to avoid having to deploy every time just to test a change to my onCall functions.

---

My code

Function :

exports.myFunction = functions.https.onCall((data, context) => {
  // Do something
});

Client:

const message = { message: 'Hello.' };

firebase.functions().httpsCallable('myFunction')(message)
  .then(result => {
    // Do something //
  })
  .catch(error => {
    // Error handler //
  });

Solution 1

For locally you must call (after firebase.initializeApp)

firebase.functions().useFunctionsEmulator('http://localhost:5000') 

Solution 2

Callables are just HTTPS functions with a specific format. You can test just like a HTTPS function, except you have to write code to deliver it the protocol as defined in the documentation.

Solution 3

There is a simple trick, how you can simplify onCall -function testing. Just declare the onCall function callback as a local function and test that instead:

export const _myFunction = (data, context) => { // <= call this on your unit tests
  // Do something
}

exports.myFunction = functions.https.onCall(_myFunction);

Now you can variate all cases with a normal function with the input you define on your function call.

Solution 4

Although the official Firebase Cloud Function docs have not yet been updated, you can now use firebase-functions-test with onCall functions.

You can see an example in their repository.

I have managed to test my TypeScript functions using jest, here is a brief example. There are some peculiarities here, like import order, so make sure to read the docs :-)

/* functions/src/test/index.test.js */
/* dependencies: Jest and jest-ts */

const admin = require("firebase-admin");
jest.mock("firebase-admin");
admin.initializeApp = jest.fn(); // stub the init (see docs)
const fft = require("firebase-functions-test")();

import * as funcs from "../index";

// myFunc is an https.onCall function
describe("test myFunc", () => {
  // helper function so I can easily test different context/auth scenarios
  const getContext = (uid = "test-uid", email_verified = true) => ({
    auth: {
      uid,
      token: {
        firebase: {
          email_verified
        }
      }
    }
  });
  const wrapped = fft.wrap(funcs.myFunc);

  test("returns data on success", async () => {
    const result = await wrapped(null, getContext());
    expect(result).toBeTruthy();
  });

  test("throws when no Auth context", async () => {
    await expect(wrapped(null, { auth: null })).rejects.toThrow(
      "No authentication context."
    );
  });
});

Solution 5

you should first check for dev environment and then point your functions to local emulator.
For JS:

//after firebase init
if (window.location.host.includes("localhost") ||
    window.location.host.includes("127.0.0.1")
) {
    firebase
      .app()
      .functions()  //add location here also if you're mentioning location while invoking function()
      .useFunctionsEmulator("http://localhost:5001");
  }

or if you don't create instance of firebase then

//after firebase init
if (window.location.host.includes("localhost") || 
   window.location.host.includes("127.0.0.1")
) {
    firebase
      .functions()
      .useFunctionsEmulator("http://localhost:5001");
  }

---

or when serving pages from backend (node.js):

//after firebase init
if (process.env.NODE_ENV === 'development') {
  firebase.functions().useFunctionsEmulator('http://localhost:5001');
}

View more solutions

Comments

[czphilip]

Awesome! I will try this out when I have access to the code. BTW is this a newly added feature?

[cbdeveloper]

This works! I was about to enter a never ending cycle of deploy-edit-deploy... This should be in the documentation guides. Thanks.

[Eli Himself]

This works just make sure you are hitting the right port it may not always be :5000, - thank you!

[Darari Nur Amali]

This is not working in my case. No method for functions().useFunctionsEmulator. Any help?

[Petr Pololáník]

My imports: import firebase from 'firebase/app'; import 'firebase/functions' // important

[alexcs]

Thanks a lot for this idea. Honestly, I feel the testing ergonomics of Firebase callables is abhorrent... Why would I need to stub / mock so many elements of the Firebase internals just to produce a valid test? I just want to check values in and values out. Your solution has the shortcoming that one can't test for the wrapped result of the Firebase callable, but I'll take it.

[Ville Venäläinen]

To go further, you can use the Firebase's emulator. I have also been developing ts-mock-firebase -library for these purposes. Currently project have been inactive, mainly because the progress that Google has done with its own emulators.

[Wesley Barnes]

Can I just comment that the onCall in the answer here should be onRequest. Thanks for the trick, it seems to work. What a mission