4.a) i) In the context of Object Oriented (OO) analysis and design. describe the role of a State Chart Diagram. ii) Using a clearly labelled diagram, identify, and outline the meaning of, the following State Chart elements:

State Event Transition

b)(i) In the context of Object Oriented (OO) system testing, outline what is meant by Unit Testing. (ii) Explain what is meant by Test Driven Development and show how it differs from a "traditional" approach to Unit Testing. (iii) Discuss the role of Mock Objects when implementing unit tests.