This document discusses testing of data warehouses. It outlines different types of data warehouse testing including testing the extraction, transformation, and loading (ETL) process. The document recommends checking data quality by ensuring completeness and proper data transformation according to business rules. It identifies four important aspects of data warehouse testing: recognizing the importance of testing, planning test phases, planning QA staffing, and avoiding risks. Key focus points for testing include underlying data and different data warehouse components. The challenges of data warehouse testing include data selection from multiple sources, large data volumes and complexity, inconsistent data, lack of a comprehensive test bed, and the critical nature of the data for business decisions.