In firebase - How to generate an idToken on the server for testing purposes?

Question

I want to test a a cloud function that creates users.

In normal cases, inside the browser i generate an idToken and i send it to server via headers: Authorization : Bearer etcIdToken

But I want to test this function without the browser. In my mocha tests i have:

before(done => {    firebase = require firebase.. -- this is suppose to be like the browser lib.    admin = require admin..       idToken = null;     uid = "AY8HrgYIeuQswolbLl53pjdJw8b2";     admin.auth()         .createCustomToken(uid)               -- admin creates a customToken         .then(customToken => {             return firebase.auth()            -- this is like browser code. customToken get's passed to the browser.                 .signInWithCustomToken(customToken)     -- browser signs in.                 .then(signedInUser => firebase.auth()             -- now i want to get an idToken. But this gives me an error.                     .currentUser.getIdToken())         })         .then(idToken_ => {             idToken = idToken_             done();         })         .catch(err => done(err)); }) 

The error i'm getting is:

firebase.auth(...).currentUser.getIdToken is not a function - getting the idToken like this works on client - and is documented here.

I tried directly with signedInUser.getIdToken(). Same problem:

signedInUser.getIdToken is not a function - not documented. just a test.

I think this is because firebase object is not intended for node.js use like i'm doing here. When signing in - stuff get's saved in browser local storage - and maybe this is why.

But the question still remains. How can i get an idToken inside node.js in order to be able to test:

return chai.request(myFunctions.manageUsers)     .post("/create")     .set("Authorization", "Bearer " + idToken)   --- i need the idToken here -  like would be if i'm getting it from the browser.     .send({           displayName: "jony",           email: "[email protected]",           password: "123456"     }) 

am I approaching this wrong? I know that if i can get the idToken it will work. Do i rely need the browser for this? Thanks :)

Answer 1

From Exchange custom token for an ID and refresh token, you can transform a custom token to an id token with the api. Hence, you just have to generate a custom token first from the uid, then transform it in a custom token. Here is my sample:

const admin = require('firebase-admin'); const config = require('config'); const rp = require('request-promise');  module.exports.getIdToken = async uid => {   const customToken = await admin.auth().createCustomToken(uid)   const res = await rp({     url: `https://www.googleapis.com/identitytoolkit/v3/relyingparty/verifyCustomToken?key=${config.get('firebase.apiKey')}`,     method: 'POST',     body: {       token: customToken,       returnSecureToken: true     },     json: true,   });   return res.idToken; }; 

Answer 2

L. Meyer's Answer Worked for me.

But, the rp npm package is deprecated and is no longer used. Here is the modified working code using axios.

const axios = require('axios').default; const admin = require('firebase-admin'); const FIREBASE_API_KEY = 'YOUR_API_KEY_FROM_FIREBASE_CONSOLE';  const createIdTokenfromCustomToken = async uid => {   try {     const customToken = await admin.auth().createCustomToken(uid);      const res = await axios({       url: `https://www.googleapis.com/identitytoolkit/v3/relyingparty/verifyCustomToken?key=${FIREBASE_API_KEY}`,       method: 'post',       data: {         token: customToken,         returnSecureToken: true       },       json: true,     });      return res.data.idToken;    } catch (e) {     console.log(e);   } }