According to the deficiency of Timed Abstract State Machine (TASM), TASM is extended with the data type of arrays, a loop rule named “while”, and some operators such as “%”,“&”, “|”, “^”, “>>”, “<<”, etc. The syntax and semantics of the extended TASM are defined. The extended TASM is applied to actual real-time embedded software to validate its effectiveness for requirements modeling.

New characteristics in component technology bring new challenges to component testing. Design by contract is an important approach to design for testability of software. Contract-based design for test ability of components provides effective means to component testing. A new tool to support design by contract is designed and implemented, which is named PKUJDBCT and can be used to support design for testability of components, and provide a basis for our future research on methods of contract-based design for testability of components.

Software testing is one of the most important techniques used to assure the quality of software products. Software testing keeps a high proportion during the whole software life cycle. Gradually, software testing develops towards the former phase of software development and inosculates with the design and coding phases of software development. This paper introduces the basic ideas of software testing from the techniques and the process of software testing, persistent software testing, adequate criteria of software testing and so on. Then, this paper discusses some problems in software testing, including automated path-wise test data generation, test oracle, automated expected results generation, regression testing and so on. At last, this paper explores the development tendency of software testing, such as component testing, software testability, design by contract for testability in components and Web Services testing.