Design patterns and object-oriented software testing

It is well known that design decisions regarding the use of design patterns can increase reusability, portability and ease maintenance activities among others. The designer's choice of design patterns can also have a major influence on the testability and testing methodology employed by the tester. Depending on the design choices made, the tester can also use additional design patterns to ease the construction of test fixtures and test case design with minimal or no intrusion of the source code. We examine the interrelationships of design choices and their influence on the testing methodology. For polymorphic class interaction, the decorator design pattern can be fruitfully employed in the testing/logging environment with minimal or no source code intrusion