feat: Multiplexed sessions - Update _builders to use mock scoped credentials.

Signed-off-by: Taylor Curran <taylor.curran@improving.com>

Author: currantw

tests/_builders.py

@@ -16,6 +16,7 @@
 from mock import create_autospec
 from typing import Mapping
 
+from google.auth.credentials import Credentials, Scoped
 from google.cloud.spanner_dbapi import Connection
 from google.cloud.spanner_v1 import SpannerClient
 from google.cloud.spanner_v1.client import Client
@@ -92,6 +93,9 @@ def build_client(**kwargs: Mapping) -> Client:
     if "project" not in kwargs:
         kwargs["project"] = _PROJECT_ID
 
+    if "credentials" not in kwargs:
+        kwargs["credentials"] = build_scoped_credentials()
+
     return Client(**kwargs)
 
 
@@ -174,6 +178,15 @@ def build_logger() -> Logger:
     return create_autospec(Logger, instance=True)
 
 
+def build_scoped_credentials() -> Credentials:
+    """Builds and returns a mock scoped credentials for testing."""
+
+    class _ScopedCredentials(Credentials, Scoped):
+        pass
+
+    return create_autospec(spec=_ScopedCredentials, instance=True)
+
+
 def build_spanner_api() -> SpannerClient:
     """Builds and returns a mock Spanner Client API for testing using the given arguments.
     Commonly used methods are mocked to return default values."""