How do I use the local Firebase Auth emulator and not production auth to test my users?

Question

My app still expects to validate users with the production firebase-auth instance, despite having initialised the auth emulator locally with:

firebase init emulators

This is the auth logic in my React app:

const handleLogin = () => 
  authentication.signInWithEmailAndPassword("emulator@test.com", "emulator");

After handleLogin is triggered, I get the error "auth/user-not-found" as firebase is querying the production auth instance instead.

Answer 1

You need to call useEmulator synchronously, right after initialisation of your app’s auth instance. useEmulator takes the local emulator URL as its only argument.

You need the following wherever your firebase auth instance is initialised:

Firebase SDK Version 9 with tree shaking

import { getAuth, connectAuthEmulator } from "firebase/auth";

const auth = getAuth();
connectAuthEmulator(auth, "http://localhost:9099");

Firebase SDK Version 8

import firebase from "./firebase-config";
import "firebase/auth";

const authentication = firebase.auth();
    
authentication.useEmulator("http://localhost:9099");
    
export default authentication;