Object Oriented Software and its Test Strategies...

In testing object oriented software, the objective of testing remains the same. The nature of object oriented software changes both testing strategy and testing tactics.

UNIT TESTING IN OBJECT ORIENTED CONTEXT
In object oriented software, an encapsulated class is the focus of unit testing. Encapsulation means that class and class object packages the attributes and operations that manipulate the data. A class contains many operations so unit testing these operations must also vary.
Class testing for object oriented software is analogous to module testing for conventional software. It is not advisable to test operations in isolation. Unit testing of conventional software focus on algorithmic detail of module and the data that flows across module whereas unit testing for object oriented software focus on operations encapsulated by class.

INTEGRATION TESTING IN OBJECT ORIENTED CONTEXT
An important strategy for integration testing of object oriented software is thread based testing. Threads are set of classes that respond to an input or event. Each thread is integrated and tested individually. Regression testing is done.
Another strategy is the use based tests that focus on classes that do not collaborate heavily with other classes.

The behavior of drivers and stubs also changes during integration testing of object oriented software. Drivers test operations at lowest level and for testing whole group of classes. Stubs are used where collaboration between classes is required but one or more collaborating class is not fully implemented.