Composite Web Service Test Cases Generation Based On Parsing XML Documents And Solving Constraints

With the development of Internet and distributed system, Service-Oriented Architecture (SOA) is widely used in both academic circles and industrial circles. As a key technique for realizing SOA, Web service has become a hot issue. In order to take full advantage of Web services and solve the problem of a single Web service’s limited function, Web service compositions are popular according to certain business rules. Therefore, it is necessary to test them comprehensively and fully so as to ensure the quality.The common testing method for composite Web services is black-box testing method, includes using WSDL interfaces, combining with ontology libraries, or based on user input. However, these methods generate test cases with high redundancy, namely a lot of test cases are invalid, and the discovery of ontology libraries in Web services is difficult, the coverage rate of test cases is still not high.Test case generation is the main research problem in software testing, and we develop a novel method to generate test cases for composite Web services by parsing XML documents and solving constraints, together with different coverage criteria. Namely, we first parse the composite Web services’interface documents based on the relationship of different XML documents, so we can get various constraints related with extensive testing information. Then we use constraint solver to get solution space and combine with coverage criteria to generate test cases. The main contributions of this paper are presented as follows:Firstly, for composite Web services only provide XML interface documents, we develop a method to parse these documents based on the relationships of different documents, such as WSDL, XSD and BPEL documents, so we can filter out irrelevant information and generate Intermediate Representations(IRs) including process flows, attribute values, definition of variables and condition statements.Secondly, we propose a method to generate test cases using constraint solving. Interface constraints are classified into variable type constraints, input and output constraints, condition constraints and order constraints. Then we present the constraint encoding rules to generate constraint documents. And we use Z3-str SMT solver to get feasible solutions and generate test cases described in SOAP.Thirdly, in order to solve the low coverage rate issues for generated test cases, we propose a method of generating test cases based on different coverage criteria, including node coverage, path coverage and MC/DC coverage. And we increase constraints to satisfy the request of different coverage criteria.Finally, we develop a tool called GTCWS to implement these methods and carry out experiments with different types of Web services provided by Oracle BPEL PM Sample and WS-BPEL Composition Repository. Then we compare our method with current work to evaluate constraint scale, coverage rate and solving time. The results show that GTCWS can generate effective test cases with high coverage rate and low redundancy, and the time spend on the tool is acceptable.