Yasufumi Toyoshima

Formal approach to scenario analysis

Scenarios offer promise as a way to tame requirements analysis, but progress has been impeded by the lack of a systematic way to analyze, generate, and validate them. The authors propose such a method and apply it to a simple PBX system. Their method has a formal mathematical base, generates precise scenarios, accommodates change, and keeps users involved in the process.<<ETX>>

On regression testing of object-oriented programs

Regression testing is an important activity in software maintenance. Although a number of studies have addressed the problems and solutions in regression testing of traditional programs, no studies have focused on the issues and solutions in regression testing of object-oriented programs. In this article, we discuss various types of code changes of classes in an object-oriented program and present a method for identifying these changes and the affected classes. An algorithm for generating a desirable order to test the affected classes is also described. The basic model we use is an object relation graph, which depicts the inheritance, aggregation, and association relations that exist in the object-oriented program to be maintained. The test order generation algorithm can be applied to acyclic as well as cyclic object relation graphs. The results of this work have been implemented and applied to testing of many example applications, including the InterViews library.

Developing an object-oriented software testing and maintenance environment

The object-oriented (OO) paradigm is rapidly gaining acceptance in the software industry. However, the powerful features of this new paradigm also introduce a new set of OO software testing and maintenance problems. The pioneering work in identifying these new problems includes [7, 10-12, 14, 16, 18]. The problems can be summarized as: 1) the understanding problem; 2) the complex interdependency problem; 3) the object state behavior testing problem; and 4) the tool support problem. Detailed discussions of these problems will be provided later. Our industrial experience confirms these discoveries.

On object state testing

The importance of object state testing is illustrated through a simple example. We show that certain errors in the implementation of object state behavior cannot be readily detected by conventional structural testing, functional testing, and state testing. We describe an object state test model and outline a reverse engineering method for extracting object state behaviors from C++ source code. The object state test model is a hierarchical, concurrent, communicating state machine. It resembles the concepts of inheritance and aggregation in the object-oriented paradigm rather than the concept of state decomposition as in some existing models. The reverse engineering method is based on symbolic execution to extract the states and effects of the member functions. The symbolic execution results are used to construct the state machines. The usefulness of the model and of the method is discussed in the context of object state testing in the detection of a state behavior error.<<ETX>>

A test strategy for object-oriented programs

The complexity and interdependencies of an object oriented program makes testing of such programs difficult. We present a reverse engineering based model called Object Relation Diagram (ORD), which is generated from analyzing the C++ source code of an object oriented program. An ORD is a directed graph in which the vertices represent the object classes and the edges represent the relationships among the object classes. Based on the ORD, a test strategy, called test order, for unit testing and integration testing of object oriented programs is described. The test order algorithm uses topological sorting and clusters of strongly connected subgraphs of the ORD. It computes the optimal test order in the sense that the effort required to construct the test stubs to simulate the untested classes/member functions is minimum. We show the savings of the test strategy through statistics of the InterViews library.

A technique for the selective revalidation of OO software

The object-orientated paradigm provides the power for software development but at the same time introduces some brand new problems. One of these problems is that the relationships among classes are more complex and difficult to identify than those in the traditional paradigm. This problem becomes a major obstacle for regression testing of OO software, in which the relationships among classes as well as those between test cases and classes, must be determined a priori. In this paper we propose a new method to select only a fraction of the test cases from the entire test suite to revalidate an OO software system. This method is based on the concepts of class firewall and of marking all the classes ‘touched’ by a test case. From the class firewall, we can identify all of the affected classes after a new version of software is released. Together with the markings, we can also identify all the test cases in the test suite that need to be retested after the software change. A step-by-step process is proposed to identify the relationships between classes and test cases, compute the class firewall, and select only the appropriate test cases for retesting.

Object state testing for object-oriented programs

Since class objects are the major components in object oriented (OO) programs during run time, testing the behavior of these objects become an important task in testing of object oriented programs to complement other types of testing, such as, structure testing and functional testing. To check the behavior of objects in OO programs, it is essential to check each state and each transition for every object. The paper proposes a new test model, called object state diagram, to capture and represent the dynamic behavior of objects in an OO program. The model is an extension of the existing state models, it supports basic OO features, such as class objects, inheritance, aggregation and overloading. Unlike other models, it is a concurrent, communicating state machine which has the capability of representing the object state hierarchy for a complex class object. Based on this model we address the issues and solutions to object state test strategy, test criteria and test generation.

Object state testing and fault analysis for reliable software systems

Object state behavior implies that the effect of an operation on an object may depend on the states of the object and other objects. It may cause state changes to more than one object. Thus, the combined or composite effects of the object operations must be analyzed and tested. We show that certain object state behavior errors cannot be detected readily by conventional testing methods. We describe an object state test method consisting of an object state model, a reverse engineering tool, and a composite object state testing tool. The object state test model is an aggregation of hierarchical, concurrent, communicating state machines envisioned mainly for object state testing. The reverse engineering tool produces an object state model from any C++ program. The composite object state testing tool analyzes the object state behaviors and generates test cases for testing object state interactions. We show the detection of several composite object state behavior errors that exist in a well-known thermostat example.

Developing an integrated testing environment using the World Wide Web technology

The World Wide Web (WWW) technology has been widely accepted and used to build different application systems on the Internet and/or Intranet due to its advantages in networking, platform independence, distributed accesses for multiple users at different locations. We believe that this new technology is a powerful and cost effective tool to build a next generation environment for supporting software engineering practice in a software products life cycle. The paper reports our experience on developing a Web based testing information sharing, control and management system using WWW technology. The paper also discusses its approach, basic function features, related design and implementation mechanisms. In addition, it reports the first hand useful experience and lessons in developing Web based software engineering support systems.

Object-oriented software testing-some research and development

It is widely accepted that the OO paradigm will significantly increase software reusability, extendibility, interoperability, and reliability. This is also true for high assurance systems engineering, provided that the systems are tested adequately. Software testing is an important software quality assurance activity to ensure that the benefits of OO programming will be realized. OO software testing has to deal with new problems introduced by the powerful new features of OO languages. The objective of the article is to review some of the existing research in OO software testing, in particular, the research at the University of Texas at Arlington.