Testing hybrid systems with TTCN-3 embedded

A testing language typically provides a set of test automation statements that allows for a systematic definition and automatic application of stimulation data (i.e. messages or signals) to a system under test. Moreover, it eases the assessment of the systemâs reaction by providing customizable evaluation statements and functions. TTCN-3, the Testing and Test Control Notation, already provides universal and powerful concepts to describe tests for discrete, message-based systems. However, software-based control systems that are used to control physical processes often show continuous quantities that can be only poorly stimulated and assessed by means of the currently available language constructs in TTCN-3. In this article, we show how this problem can be solved by extending the TTCN-3 language. We introduce an extension of TTCN-3, namely TTCN-3 embedded, that provides concepts and constructs that directly address the specification of tests for continuous and hybrid real time systems. The extension includes the notion of streams that can be used to represent continuous quantities over time. In addition, TTCN-3 has been extended with the concepts of stream-based ports, sampling, equation systems, and with additional control flow structures. The concepts are integrated with standard TTCN-3 and allow for defining test cases that handle continuous quantities, as well as discrete state changes and the exchange of messages within the same concept space. The feasibility of the approach is shown by providing a small example from the automotive industry.