The Issue: The ETL development process above is typically a complete black box. The business users or business analysts don’t really have any insights into the quality or correctness of this ETL process. Hence it is not only important to test this ETL Process, but ensure that the – ETL testing is transparent to the user’s data warehouse testing needs. Also, it’s not enough to test based on the transformation rules alone, since the technical transformation requirements might be incorrect and may not represent true business requirements.