Several module and class testing techniques have been applied to object-oriented programs, but researchers have only recently begun developing test criteria that evaluate the use of key OO features such as inheritance, polymorphism, and encapsulation. Mutation testing is a powerful testing technique for generating software tests and evaluating the quality of software. However, the cost of mutation testing has traditionally been so high it cannot be applied without full automated tool support. This paper presents a method to reduce the execution cost of mutation testing for OO programs by using two key technologies, Mutant Schemata Generation (MSG) and bytecode translation. This method adapts the existing MSG method for mutants that change the program behavior and uses bytecode translation for mutants that change the program structure. A key advantage is in performance: only two compilations are required and both the compilation and execution time for each is greatly reduced. A mutation tool based on the MSG/bytecode translation method has been built and used to measure the speedup over the separate compilation approach. Experimental results show that the MSG/bytecode translation method is about five times faster than separate compilation.

Testing is an important process that is performed to support quality assurance. Testing activities support quality assurance by gathering information about the nature of the software being studied. These activities consist of designing test cases, executing the software with those test cases, and examining the results produced by those executions. Studies indicate that more than fifty percent of the cost of software development is devoted to testing, with the percentage for testing critical software being even higher. As software becomes more pervasive and is used more often to perform critical tasks, it will be required to be of higher quality. Unless we can find efficient ways to perform effective testing, the percentage of development costs devoted to testing will increase significantly. This report briefly assesses the state of the art in software testing, outlines some future directions in software testing, and gives some pointers to software testing resources.

Abstract. Researchers and practitioners are still trying to find effective ways to model and test Web applications. This paper proposes a system-level testing technique that combines test generation based on finite state machines with constraints. We use a hierarchical approach to model potentially large Web applications. The approach builds hierarchies of Finite State Machines (FSMs) that model subsystems of the Web applications, and then generates test requirements as subsequences of states in the FSMs. These subsequences are then combined and refined to form complete executable tests. The constraints are used to select a reduced set of inputs with the goal of reducing the state space explosion otherwise inherent in using FSMs. The paper illustrates the technique with a running example of a Web-based course student information system and introduces a prototype implementation to support the technique.

Object-oriented programming consists of several different levels of abstraction, namely the algorithmic level, class level, cluster level, and system level. The testing of object-oriented software at the algorithmic and system levels is similar to conventional programming testing. Testing at the class and cluster levels poses new challenges. Since methods and objects may interact with one another dynamically with unforeseen combinations and invocations, they are much more complex to simulate and test than the static hierarchy of functional calls in conventional programs. In this paper, we propose a methodology for object-oriented software testing at the class and cluster levels. In class-level testing, it is essential to determine whether objects produced from the execution of implemented systems would preserve the properties defined by the specification, such as behavioral equivalence and non-equivalence. Our class-level testing methodology addresses both of these aspects. For the testing of behavioral equivalence, we propose to select fundamental pairs of equivalent ground terms as test cases using a black-box technique based on algebraic specifications, and then determine by means of a white-box technique whether the objects resulting from executing such test cases are observationally equivalent. To address the testing of behavioral non-equivalence, we have identified and analyzed several non-trivial problems in the current literature. We propose to classify term equivalence into four types, thereby setting up new concepts and deriving important properties. Based on these results, we propose an approach to deal with the problems in the generation of non-equivalent ground terms as test cases. Relatively little research has contributed to cluster-level testing. In this paper, we also discuss black-box testing at the cluster level. We illustrate the feasibility of using Contract, a formal specification language for the behavioral dependencies and interactions among cooperating objects of different classes in a given cluster. We propose an approach to test the interactions among different classes using every individual message-passing rule in the given Contract specification. We also present an approach to examine the interactions among composite message-passing rules. We have developed four testing tools to support our methodology.

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 the broadcast communication is 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.

Abstract 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). In this paper, 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 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. 1

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The mutation method assesses test quality by examining the ability of a test set to distinguish syntactic deviations representing specific types of faults from the program under test. This paper describes an empirical study performed to evaluate the effectiveness of object-oriented (OO) test strategies using the mutation method. The test sets for the experimental system are generated according to three selected OO test methods and their effectiveness is compared by determining how well the developed test sets kill injected mutants derived from an established mutation system Mothra, and our own OO-specific mutation technique which is termed Class Mutation.

This paper describes an empirical investigation of the cost effectiveness of well-known state-based testing techniques for classes or clusters of classes that exhibit a state-dependent behavior. This is practically relevant as many object-oriented methodologies recommend modeling such components with statecharts which can then be used as a basis for testing. Our results, based on a series of three experiments, show that in most cases state-based techniques are not likely to be sufficient by themselves to catch most of the faults present in the code. Though useful, they need to be complemented with black-box, functional testing. We focus here on a particular technique, Category Partition, as this is the most commonly used and referenced black-box, functional testing technique. Two different oracle strategies have been applied for checking the success of test cases. One is a very precise oracle checking the concrete state of objects whereas the other one is based on the notion of state invariant (abstract states). Results show that there is a significant difference between them, both in terms of fault detection and cost. This is therefore an important choice to make that should be driven by the characteristics of the component to be tested, such as its criticality, complexity, and test budget.

The complexity and interdependencies of an object-oriented program makes testing of such programs difficult. In this paper, we present a reverse engineering based model called Object Relation Diagram (ORD), which is generated from analyzing the C++ source code of an objectoriented 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. 1 Introduction The object-oriented (OO) paradigm is rapidly expandi...