A system and method determine the possibility of adverse effect arising from a code change in a computer program. The system and method comprise the steps of identifying important classes within a computer program and determining directly and indirectly dependent classes of the important classes. The important classes comprise superclasses of the directly and indirectly dependent classes. The method associates test cases with the important classes and with the directly and indirectly dependent classes. Additionally, for a given code change to first important class, the method runs all test cases associated with the first important class and associated with dependent classes of the first important class, and indicates the possibility of an adverse effect if any run test case fails.