Tests were executed on different levels: on module, integration and system test level. Much emphasis was on early unit tests, which accounted for more than 50% of the test automation code. Automated integration test techniques were applied to test the interaction between the business layer and the data access layer, without interacting directly with the user interface. System tests were restricted to the verification of the most important functions only, and the system test automation code only accounted for about 20% of all test code. Test cases were reused for load and volume tests. A suite of manual system tests, which lasted for about one day, complemented the automated system tests