From a96edc85d3ccf67cb539dc55c36b27d38b95572f Mon Sep 17 00:00:00 2001
From: Jonathan Edey <jedey@google.com>
Date: Thu, 24 Oct 2024 15:27:55 -0400
Subject: [PATCH 1/2] feat: Support passing `google.auth` typed credentials in
 `initialize_app()`

---
 firebase_admin/__init__.py    |  3 +++
 firebase_admin/credentials.py | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/firebase_admin/__init__.py b/firebase_admin/__init__.py
index 0ca82ec5e..2a669ccc0 100644
--- a/firebase_admin/__init__.py
+++ b/firebase_admin/__init__.py
@@ -18,6 +18,7 @@
 import os
 import threading
 
+from google.auth.credentials import Credentials as GoogleAuthCredentials
 from google.auth.exceptions import DefaultCredentialsError
 from firebase_admin import credentials
 from firebase_admin.__about__ import __version__
@@ -208,6 +209,8 @@ def __init__(self, name, credential, options):
                              'non-empty string.'.format(name))
         self._name = name
 
+        if isinstance(credential, GoogleAuthCredentials):
+            credential = credentials._ExternalCredentials(credential)
         if not isinstance(credential, credentials.Base):
             raise ValueError('Illegal Firebase credential provided. App must be initialized '
                              'with a valid credential instance.')
diff --git a/firebase_admin/credentials.py b/firebase_admin/credentials.py
index 5477e1cf7..750600280 100644
--- a/firebase_admin/credentials.py
+++ b/firebase_admin/credentials.py
@@ -18,6 +18,7 @@
 import pathlib
 
 import google.auth
+from google.auth.credentials import Credentials as GoogleAuthCredentials
 from google.auth.transport import requests
 from google.oauth2 import credentials
 from google.oauth2 import service_account
@@ -58,6 +59,19 @@ def get_credential(self):
         """Returns the Google credential instance used for authentication."""
         raise NotImplementedError
 
+class _ExternalCredentials(Base):
+    """A wrapper for google.auth.credentials.Credentials typed credential instances"""
+
+    def __init__(self, credential: GoogleAuthCredentials):
+        super(_ExternalCredentials, self).__init__()
+        self._g_credential = credential
+
+    def get_credential(self):
+        """Returns the underlying Google Credential
+
+        Returns:
+          google.auth.credentials.Credentials: A Google Auth credential instance."""
+        return self._g_credential
 
 class Certificate(Base):
     """A credential initialized from a JSON certificate keyfile."""

From fc8b8d451de53b06edd80649d5bd5d7e9b2cbe3e Mon Sep 17 00:00:00 2001
From: Jonathan Edey <jedey@google.com>
Date: Mon, 28 Oct 2024 11:18:38 -0400
Subject: [PATCH 2/2] Refactor and add unit test

---
 firebase_admin/__init__.py |  7 ++++---
 tests/test_app.py          | 10 ++++++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/firebase_admin/__init__.py b/firebase_admin/__init__.py
index 2a669ccc0..7bb9c59c2 100644
--- a/firebase_admin/__init__.py
+++ b/firebase_admin/__init__.py
@@ -210,11 +210,12 @@ def __init__(self, name, credential, options):
         self._name = name
 
         if isinstance(credential, GoogleAuthCredentials):
-            credential = credentials._ExternalCredentials(credential)
-        if not isinstance(credential, credentials.Base):
+            self._credential = credentials._ExternalCredentials(credential) # pylint: disable=protected-access
+        elif isinstance(credential, credentials.Base):
+            self._credential = credential
+        else:
             raise ValueError('Illegal Firebase credential provided. App must be initialized '
                              'with a valid credential instance.')
-        self._credential = credential
         self._options = _AppOptions(options)
         self._lock = threading.RLock()
         self._services = {}
diff --git a/tests/test_app.py b/tests/test_app.py
index 4233d5849..5b203661f 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -246,6 +246,16 @@ def test_non_default_app_init(self, app_credential):
         with pytest.raises(ValueError):
             firebase_admin.initialize_app(app_credential, name='myApp')
 
+    def test_app_init_with_google_auth_cred(self):
+        cred = testutils.MockGoogleCredential()
+        assert isinstance(cred, credentials.GoogleAuthCredentials)
+        app = firebase_admin.initialize_app(cred)
+        assert cred is app.credential.get_credential()
+        assert isinstance(app.credential, credentials.Base)
+        assert isinstance(app.credential, credentials._ExternalCredentials)
+        with pytest.raises(ValueError):
+            firebase_admin.initialize_app(app_credential)
+
     @pytest.mark.parametrize('cred', invalid_credentials)
     def test_app_init_with_invalid_credential(self, cred):
         with pytest.raises(ValueError):