Contract-Based Testing for Web Services

This paper examines the use of Design by Contract for web service descriptions, and explores the issues and solutions of automatic test case generation and test oracle generation in the context of WS testing based on contracts. In our approach, the traditional concept of contracts (pre-condition, post-condition, and invariant) is extended to contain richer information, such as process control, to support automatic test generation. Contracts are used to specify the relation between a component and its clients as a formal agreement, expressing each party´s rights and obligations. Contracts can be expressed in the OWL-S process model. By checking whether the web service respects its contracts, we can ascertain its validity. Therefore, contracts provide the basis for the automation of the testing process.