Passive Testing of Symbolic Systems. A IOCO Proxy-Tester Based Approach.

This paper, dealing with model-based testing, proposes to formalize the concept of IOCO proxy-tester for passively testing the conformance of implementations. This proxy oriented approach is particularly interesting when the implementation environment access is restricted, for security or technical reasons. In this case, a proxy-tester can be installed outside of this environment to interact with the implementation. It represents an intermediary application which receives the client traffic, forwards it to an implementation and vice-versa. While passively observing the implementation reactions, it can also detect its incorrect behaviours. We present, in the paper, a formal IOCO proxy-tester definition that can be used to automatically generate one proxy-tester from a ioSTS specification. The notion of conformance is defined with the ioco test relation. To directly check whether the implementation is IOCO-conforming to its specification by means of a proxy-tester, we rephrase IOCO by defining sets of partial traces extracted from the proxy-tester. We also introduce other possibilities offered by the proxy-tester concept. In particular, we describe an approach which improves the functional quality of the implementation by completing its proxy-tester. [ABSTRACT FROM AUTHOR]