failed test cases

Author: surbhigarg92

google/cloud/spanner_v1/_helpers.py

@@ -724,4 +724,5 @@ def _merge_Transaction_Options(
     # Merge transactionOptions, ensuring it overrides default values
     merged_pb.MergeFrom(mergeTransactionOptions._pb)
 
-    return merged_pb
+    # Convert protobuf object back into a TransactionOptions instance
+    return TransactionOptions(merged_pb)

tests/unit/test_session.py

@@ -1812,7 +1812,9 @@ def test_run_in_transaction_w_isolation_level_at_request_overrides_client(self):
         gax_api = self._make_spanner_api()
         gax_api.begin_transaction.return_value = TransactionPB(id=b"FACEDACE")
         database = self._make_database(
-            default_transaction_options={"isolation_level": "SERIALIZABLE"}
+            default_transaction_options=DefaultTransactionOptions(
+                isolation_level="SERIALIZABLE"
+            )
         )
         database.spanner_api = gax_api
         session = self._make_one(database)