Uma técnica para verificar não conformidades em programas especificados com contratos.

Abstract

Writing formal specifications by contracts is a practical and reliable way to build softwares in which developers and clients keep an agreement with rights and obligations to be fulfilled. These responsibilities are expressed basically by pre-conditions, post-conditions and invariants. As example of specification language by contract there is Java Modeling Language (JML) that is specific to Java programs. Although formal specification improves software rehabihty, it should exist certification of conformance with defined specification. Verify conformance between programs and contracts is usually performed by manual analysis or dynamic verification, and in late stages of software development process, that is, when the final product is available to client. In this situation, the time required to detect nonconformances could be so long, causing, consequently, schedule delays and increased costs. In this work, we propose an approach to check conformance between source code and contract formal specification through testing generation and execution. Unit tests are generated automatically resulting in test cases with call sequences of methods and constructors. The contracts are translated in assertions that work like test oracle. We have implemented JMLOK, a tool performs the approach steps automatically in the context of Java programs specified with Java Modeling Language (JML). JMLOK was evaluated in Java/JML programs groups, including a module of the JavaCard project. All the experimental units totalize 18 KLOC and 5K lines of JML specification. All process took less than 10 minutes of running and generated as result 29 nonconformances. The causes of nonconformances occurring were analyzed manually and classified in categories of fails.