Hyoung Seok Hong

Test cases generation from UML state diagrams

The paper discusses the application of state diagrams in UML to class testing. A set of coverage criteria is proposed based on control and data flow in UML state diagrams and it is shown how to generate test cases satisfying these criteria from UML state diagrams. First, control flow is identified by transforming UML state diagrams into extended finite state machines (EFSMs). The hierarchical and concurrent structure of states is flattened and broadcast communications are eliminated in the resulting EFSMs. Second, data flow is identified by transforming EFSMs into flow graphs to which conventional data flow analysis techniques can be applied.

A Temporal Logic Based Theory of Test Coverage and Generation

This paper presents a theory of test coverage and generation from specifications written in EFSMs. We investigate a family of coverage criteria based on the information of control flow and data flow and characterize them in the branching time temporal logic CTL. We discuss the complexity of minimal cost test generation and describe a method for automatic test generation which employs the capability of model checkers to construct counterexamples. Our approach extends the range of applications of model checking from formal verification of finite state systems to test generation from finite state systems.

Data flow testing as model checking

This paper presents a model checking-based approach to dataflow testing. We characterize dataflow oriented coverage criteria in temporal logic such that the problem of test generation is reduced to the problem of finding witnesses for a set of temporal logic formulas. The capability of model checkers to construct witnesses and counterexamples allows test generation to be fully automatic. We discuss complexity issues in minimal cost test generation and describe heuristic test generation algorithms. We illustrate our approach using CTL as temporal logic and SMV as model checker.

A test sequence selection method for statecharts

This paper presents a method for the selection of test sequences from statecharts. It is shown that a statechart can be transformed into a flow graph modelling the flow of both control and data in the statechart. The transformation enables the application of conventional control and data flow analysis techniques to test sequence selection from statecharts. The resulting set of test sequences provides the capability of determining whether an implementation establishes the desired flow of control and data expressed in statecharts. Copyright

Testing of object-oriented programs based on finite state machines

In object-oriented testing literature, a class is considered to be a basic unit of testing. A major characteristic of classes is the interaction between data members and member functions. This interaction is represented as definitions and uses of data members in member functions and can be properly modeled with finite state machines (FSM). We discuss how FSMs can be effectively used for class testing. We demonstrate how to specify the behavior of classes using FSMs and present a test case generation technique based on FSMs. In our technique, FSMs are transformed into a flow of the graph from which we can explicitly identify data flows of the FSM. Then we generate test cases using conventional data flow testing techniques upon the flow graph.

Abstract slicing: a new approach to program slicing based on abstract interpretation and model checking

This paper proposes a new approach to program slicing based on abstract interpretation and model checking. First, the notion of abstract slicing is introduced. Abstract slicing extends static slicing with predicates and constraints by using as the program model an abstract state graph, which is obtained by applying predicate abstraction to a program, rather than a flow graph. This leads to a program slice that is more precise and smaller than its static counterpart. Second, a method for performing abstract slicing is developed. It is shown that abstract slicing can be reduced to a least fixpoint computation over formulas in the branching time temporal logic CTL. This enables one to use symbolic model checkers for CTL as an efficient computation engine for abstract slicing. A prototype implementation and experimental results are reported demonstrating the feasibility of the approach.

Using model checking for reducing the cost of test generation

This paper presents a method for reducing the cost of test generation. A spanning set for a coverage criterion is a set of entities such that exercising every entity in the spanning set guarantees exercising every entity defined by the coverage criterion. The central notion used in constructing a minimum spanning set is subsumption relation. An entity subsumes another entity if exercising the former guarantees exercising the latter. We develop a method for finding subsumption relations which can be uniformly applied to a family of control flow and data flow oriented coverage criteria by reducing the problem of determining whether an entity subsumes another entity to the model checking problem of the linear temporal logic LTL.

Dependence testing: extending data flow testing with control dependence

This paper presents a new approach to structural testing, called dependence testing. First we propose dependence oriented coverage criteria that extend conventional data flow oriented coverage criteria with control dependence. This allows one to capture the full dependence information of a program or specification systematically. We then describe a model checking-based approach to test generation for dependence testing. It is shown that dependence oriented coverage criteria can be characterized in the temporal logics LTL and CTL. This enables one to use any LTL and CTL model checkers as test generators. Finally, we show that the temporal logic-based characterization can also be used for reducing the cost of dependence testing.

Static semantics and priority schemes for statecharts

A statechart is an extended form of conventional finite state machines for specifying reactive systems. Though the graphical syntax of statecharts has been defined, there remain concepts that are still ambiguous or need to be improved. In this paper, we formally define static semantics of statecharts. And we identify the types of nondeterminism in statecharts and give alternative ways of representing priority.

Safety analysis using coloured Petri nets

The authors propose a safety analysis method using coloured Petri nets (CPN). Their method employs a backward approach where a hazard is assumed to have occurred and backward simulation from the hazard is performed in order to determine if and how the hazard might occur. Using CPN, they define a hazard as a set of markings and perform backward simulation by generating a reachability graph backwards from the hazard. To facilitate the safety analysis, they extend the semantics of CPN and define backward reachability graphs of CPN. To demonstrate their method, a shutdown system for a Korean nuclear power plant is used as an example.