Objective measurement of test quality is one of the key issues in software testing. It has been a major research focus for the last two decades. Many test criteria have been proposed and studied for this purpose. Various kinds of rationales have been presented in support of one criterion or another. We survey the research work in this area. The notion of adequacy criteria is examined together with its role in software dynamic testing. A review of criteria classification is followed by a summary of the methods for comparison and assessment of criteria.

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Petri nets have been extensively used in the modelling and analysis of concurrent and distributed systems. The verification and validation of Petri nets are of particular importance in the development of concurrent and distributed systems. As a complement to formal analysis techniques, testing has been proven to be effective in detecting system errors and is easy to apply. An open problem is how to test Petri nets systematically, effectively and efficiently. An approach to solve this problem is to develop test criteria so that test adequacy can be measured objectively and test cases can be generated efficiently, even automatically. In this paper, we present a methodology of testing high-level Petri nets based on our general theory of testing concurrent software systems. Four types of testing strategies are investigated, which include state-oriented testing, transition-oriented testing, flow-oriented testing and specification-oriented testing. For each strategy, a set of schemes to observe and record testing results and a set of coverage criteria to measure test adequacy are defined. The subsumption relationships and extraction relationships among the proposed testing methods are systematically investigated and formally proved.

In a pattern-oriented software design process, design decisions are made by selecting and instantiating appropriate patterns, and composing them together. In our previous work, we enabled these decisions to be formalized by defining a set of operators on patterns with which instantiations and compositions can be represented. In this article, we investigate the algebraic properties of these operators. We provide and prove a complete set of algebraic laws so that equivalence between pattern expressions can be proven. Furthermore, we define an always-terminating normalization of pattern expression to a canonical form which is unique modulo equivalence in first-order logic. By a case study, the pattern-oriented design of an extensible request-handling framework, we demonstrate two practical applications of the algebraic framework. First, we can prove the correctness of a finished design with respect to the design decisions made and the formal specification of the patterns. Second, we can even derive the design from these components.

The formal specification of design patterns is widely recognized as being vital to their effective and correct use in software development. It can clarify the concepts underlying patterns, eliminate ambiguity and thereby lay a solid foundation for tool support. This paper further advances a formal meta-modelling approach that uses first order predicate logic to specify design patterns. In particular, it specifies both structural and behavioural features of design patterns and systematically captures the variants in a well-structured format. The paper reports a case study involving the formal specification of all 23 patterns in the Gang of Four catalog. It demonstrates that the approach improves the accuracy of pattern specifications by covering variations and clarifying the ambiguous parts of informal descriptions.