Firebase throws "auth / network-request-failed" to signInAnonymously () while running jest tests

Question

I am writing several tests for my application (this is a build using create-responsive application) using firebase, and I am trying to anonymously log into my test database. But authentication fails. However, all other Firebase operations (CRUD) work just fine.

I can also log in anonymously from my application, which runs in a browser.

The code is very simple:

import firebase from 'firebase';
firebase
    .auth()
    .signInAnonymously()
    .catch((err) => {
        console.log(err);
    });

gives me this back:

O {
  code: 'auth/network-request-failed',
  message: 'A network error (such as timeout, interrupted connection or unreachable host) has occurred.'
}

But in fact, I see users who appear in the Firebase console:

Anonymous access is enabled:

And here are my access rules. But it never comes down to dealing with the rules, since I cannot enter.

{
  "rules": {
    "users": {
      "$user_id": {
        ".read": "$user_id === auth.uid",
        ".write": "$user_id === auth.uid"
      }
    }
  }
}

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!