Repository: googleapis/google-auth-library-python

Issue:
Expose the full response from the token server
`refresh` on oauth2 Credentials should store the full response from the token server. There is potentially useful data here, like the `id_token`.


Discussion:

Resolving patch:
diff --git a/google/oauth2/credentials.py b/google/oauth2/credentials.py
--- a/google/oauth2/credentials.py
+++ b/google/oauth2/credentials.py
@@ -39,14 +39,16 @@
 class Credentials(credentials.Scoped, credentials.Credentials):
     """Credentials using OAuth 2.0 access and refresh tokens."""
 
-    def __init__(self, token, refresh_token=None, token_uri=None,
-                 client_id=None, client_secret=None, scopes=None):
+    def __init__(self, token, refresh_token=None, id_token=None,
+                 token_uri=None, client_id=None, client_secret=None,
+                 scopes=None):
         """
         Args:
             token (Optional(str)): The OAuth 2.0 access token. Can be None
                 if refresh information is provided.
             refresh_token (str): The OAuth 2.0 refresh token. If specified,
                 credentials can be refreshed.
+            id_token (str): The Open ID Connect ID Token.
             token_uri (str): The OAuth 2.0 authorization server's token
                 endpoint URI. Must be specified for refresh, can be left as
                 None if the token can not be refreshed.
@@ -63,6 +65,7 @@ def __init__(self, token, refresh_token=None, token_uri=None,
         super(Credentials, self).__init__()
         self.token = token
         self._refresh_token = refresh_token
+        self._id_token = id_token
         self._scopes = scopes
         self._token_uri = token_uri
         self._client_id = client_id
@@ -79,6 +82,17 @@ def token_uri(self):
         URI."""
         return self._token_uri
 
+    @property
+    def id_token(self):
+        """Optional[str]: The Open ID Connect ID Token.
+
+        Depending on the authorization server and the scopes requested, this
+        may be populated when credentials are obtained and updated when
+        :meth:`refresh` is called. This token is a JWT. It can be verified
+        and decoded using :func:`google.oauth2.id_token.verify_oauth2_token`.
+        """
+        return self._id_token
+
     @property
     def client_id(self):
         """Optional[str]: The OAuth 2.0 client ID."""
@@ -106,10 +120,12 @@ def with_scopes(self, scopes):
 
     @_helpers.copy_docstring(credentials.Credentials)
     def refresh(self, request):
-        access_token, refresh_token, expiry, _ = _client.refresh_grant(
-            request, self._token_uri, self._refresh_token, self._client_id,
-            self._client_secret)
+        access_token, refresh_token, expiry, grant_response = (
+            _client.refresh_grant(
+                request, self._token_uri, self._refresh_token, self._client_id,
+                self._client_secret))
 
         self.token = access_token
         self.expiry = expiry
         self._refresh_token = refresh_token
+        self._id_token = grant_response.get('id_token')


Test patch:
diff --git a/tests/oauth2/test_credentials.py b/tests/oauth2/test_credentials.py
--- a/tests/oauth2/test_credentials.py
+++ b/tests/oauth2/test_credentials.py
@@ -58,6 +58,7 @@ def test_create_scoped(self):
     def test_refresh_success(self, now_mock, refresh_grant_mock):
         token = 'token'
         expiry = _helpers.utcnow() + datetime.timedelta(seconds=500)
+        grant_response = {'id_token': mock.sentinel.id_token}
         refresh_grant_mock.return_value = (
             # Access token
             token,
@@ -66,7 +67,7 @@ def test_refresh_success(self, now_mock, refresh_grant_mock):
             # Expiry,
             expiry,
             # Extra data
-            {})
+            grant_response)
         request_mock = mock.Mock()
 
         # Refresh credentials
@@ -80,6 +81,7 @@ def test_refresh_success(self, now_mock, refresh_grant_mock):
         # Check that the credentials have the token and expiry
         assert self.credentials.token == token
         assert self.credentials.expiry == expiry
+        assert self.credentials.id_token == mock.sentinel.id_token
 
         # Check that the credentials are valid (have a token and are not
         # expired)
diff --git a/tests/oauth2/test_service_account.py b/tests/oauth2/test_service_account.py
--- a/tests/oauth2/test_service_account.py
+++ b/tests/oauth2/test_service_account.py
@@ -162,7 +162,9 @@ def test__make_authorization_grant_assertion_subject(self):
     def test_refresh_success(self, jwt_grant_mock):
         token = 'token'
         jwt_grant_mock.return_value = (
-            token, _helpers.utcnow() + datetime.timedelta(seconds=500), None)
+            token,
+            _helpers.utcnow() + datetime.timedelta(seconds=500),
+            {})
         request_mock = mock.Mock()
 
         # Refresh credentials