Software Engineering is an evolving discipline and still very much in its nascent stage based on the conventional engineering disciplines. One of the principal challenges of software engineering is the wide gap between the principles taught in the academia and those that are practised in the industry. Being a human intensive industry software engineering has its own set of issues and challenges very different from the conventional engineering disciplines. Software development process mostly deals with "intangible entities" right from its inception through all the phases of its development life cycle. This book proposes a graph based approach for representing an object-oriented software system through its different phases of software development life cycle, and presents analysis to evaluate scenario paths in each phase that would help in designing effective test cases.