Unit testing BLL?

It is very typical and normal for software engineers to use test data instead of production data. Organizations should have a complete test database that is maintained. It is normal for there to be test systems that are separate computers from production systems. It is also normal for programming specifications for new or modified programs to include test cases that are to be used to test a system. The test cases might be used by the user to decide whether to accept the project. Many times the user that provides the request also provides test cases. The test cases can be data that already exists in the test database or the test cases could be added for testing in the future. Test cases would be especially relevant if the modification fixes a bug or bugs and inclusion of the text cases in the test database might help catch bugs in the future.