Stéphane Barbey

A Theory of Specification-Based Testing for Object-Oriented Software

The current strategies for testing object-oriented software all lack the formal basis which is necessary to perform this task efficiently. We propose the adaptation to object-oriented software of an existing theory of testing for stateless ADTs, to find errors in a class by checking that its implementation meets its specification. We present shortly in an informal way an object-oriented language, CO-OPN/2, in which language we will write the specification. We introduce a notion of test that takes into account the possible and impossible sequences of call of class methods. We examine the black-box test procedure, and give techniques to select a finite and pertinent test set from an exhaustive test set, including all the possible behaviors of the class under test, by applying test reduction hypothesis. We also study the construction of an oracle, the procedure that analyses the results of the tests, adapted to object-oriented software.

Test selection for object-oriented software based on formal specifications

We propose a method of test selection based on formal specifications, for functional testing of object-oriented software. This method is based on rigorous theoretical foundations. To limit the size of test sets, we present several hypotheses specific to object-oriented systems, used to reduce an exhaustive test set into a pertinent test set while preserving its qualities: regularity hypotheses are used to constrain the shape of tests while uniformities, with or without subdomain decomposition, are used to limit the values of the variables appearing in the tests. Care is taken to provide a method for which operational methods can be implemented.

Testing Ada Abstract Data Types Using Formal Specifications

The purpose of this paper is to present an experiment with formal methods for the black-box testing of reusable abstract data types (ADTs). We propose to test a family of software components by re-engineering a formal specification from an existing Ada implementation, using algebraic specifications. From this well-defined basis, we generate test sets automatically, by constructing an exhaustive set of formulae that prove the property preservations of a program with respect to its specifications, and by reducing this set to a finite size by applying reduction hypotheses. Once the selection of a finite test set has been performed, we show how to build the oracle, the decision procedure for the success or the failure of a test set. Finally, we discuss the advantages of test sets generated from the formal specification over those defined by a programmer, based on his intuitive understanding of the behavior of the ADT.

Testing Ada 95 Object-Oriented Programs

We show some of the specific problems for testing software introduced by the object-oriented features of Ada 95, and focus on specificationbased testing, since this strategy is the key strategy for testing object-oriented software. We present a theory for testing software by refinement of an exhaustive test set into a finite test set using three reduction hypothesis. We also show how the Oracle problem can be partially solved using some particular features of Ada 95.

Working with Ada 9X classes

Ada 9X refines the Ada 83 concept of class and introduces class-wide types to support run-time polymorphism. We study how the Ada definition of class compares to other definitions of this term. We examine how run-time polymorphism is introduced in Ada 9X, how it relates to the different concepts of subtype, and how it compares with other forms of polymorphism. We also discuss the different uses of class-wide types, mainly as a means for dynamic binding (dispatching). However, since Ada 9X has adhered to the philosophy of building blocks, class-wide entities can be used for other purposes than dispatching. These uses are idioms that every programmer should be aware of. Some of these idioms are presented here. We also examine how classes are integrated with generics.

Quality-for-ASIS: A Portable Testing Facility for ASIS

This paper describes the project Quality-for-ASIS, aiming at the development of an extensive testing facility for ASIS implementations. First the specific problems and requirements are presented. After a section about the basic concepts of ASIS and after a short introduction to testing, the designs and implementations for testing important subsets of ASIS are described. Finally, adequacy coverage statistics for a test set based on the ACVC compiler validation suite are provided.

Ada 95 as implementation language for object-oriented designs

In this paper, we show how Ada 95 can be used as an implementation language for object-oriented designs. We present a strategy to map Fusion class descriptions into Ada specifications, considering the various kinds of qualifiers that can be applied to attributes, and the various ways methods can be mapped. We also discuss issues such as naming conventions, mapping of operations, use of mixins and of generics. Finally, we show how bidirectional associations, that usually end up in a mutual dependency, can be implemented in Ada 95.

Experiences in object-oriented programming (panel session)

During the revision of Ada, the rules for object-oriented programming were carefully reviewed and tried on small examples. However, Ada 95 has now been put to use in “real” projects. Two years ago, a panel entitled “early experiences with Ada 9X program organization” described first experiences with Ada95 using the beta version of a compiler. The goal of this panel is to renew this discussion, now that the language definition is complete, that more complete development environments have found their way to the programmer, and especially that we have more experience with its features.