fix: avoid losing the original '_include_email' parameter in impersonated credentials (#626)

Co-authored-by: Tres Seaver <tseaver@palladion.com>

Author: pietrodn

packages/google-auth/google/auth/impersonated_credentials.py

@@ -341,13 +341,15 @@ def from_credentials(self, target_credentials, target_audience=None):
         return self.__class__(
             target_credentials=self._target_credentials,
             target_audience=target_audience,
+            include_email=self._include_email,
             quota_project_id=self._quota_project_id,
         )
 
     def with_target_audience(self, target_audience):
         return self.__class__(
             target_credentials=self._target_credentials,
             target_audience=target_audience,
+            include_email=self._include_email,
             quota_project_id=self._quota_project_id,
         )
 

packages/google-auth/tests/test_impersonated_credentials.py

@@ -368,12 +368,13 @@ def test_id_token_from_credential(
         assert not credentials.expired
 
         id_creds = impersonated_credentials.IDTokenCredentials(
-            credentials, target_audience=target_audience
+            credentials, target_audience=target_audience, include_email=True
         )
         id_creds = id_creds.from_credentials(target_credentials=credentials)
         id_creds.refresh(request)
 
         assert id_creds.token == ID_TOKEN_DATA
+        assert id_creds._include_email is True
 
     def test_id_token_with_target_audience(
         self, mock_donor_credentials, mock_authorizedsession_idtoken
@@ -396,12 +397,15 @@ def test_id_token_with_target_audience(
         assert credentials.valid
         assert not credentials.expired
 
-        id_creds = impersonated_credentials.IDTokenCredentials(credentials)
+        id_creds = impersonated_credentials.IDTokenCredentials(
+            credentials, include_email=True
+        )
         id_creds = id_creds.with_target_audience(target_audience=target_audience)
         id_creds.refresh(request)
 
         assert id_creds.token == ID_TOKEN_DATA
         assert id_creds.expiry == datetime.datetime.fromtimestamp(ID_TOKEN_EXPIRY)
+        assert id_creds._include_email is True
 
     def test_id_token_invalid_cred(
         self, mock_donor_credentials, mock_authorizedsession_idtoken