Test specifications for test automation: Easily created using a tool instead of a script

Test automation and intelligent solutions for creating test case specifications significantly improve the efficiency of hardware-in-the-loop (HiL) tests. Tool extensions can be used to create executable test specifications for automated HiL tests without the use of a scripting language.

Initial situation

HiL systems are widely used in industry and enable powerful test environments to be set up and test coverage to be increased. HiL tests offer a number of advantages over other test methods. Compared to tests in a real environment, HiL tests allow early testing in all development phases. They also enable better reproducibility of test cases, as the simulated environment of the test object ensures that the test process is independent of external factors such as weather conditions. In addition, the HiL test environment avoids risks from damage to the overall system and accidents during the test process that could result from possible defects – an additional cost saving. Other test methods that also use simulation techniques, such as software-in-the-loop (SiL) or model-in-the-loop (MiL), have the disadvantage that the software to be tested is not executed on the actual hardware and its interaction with external components cannot be observed. In addition, the HiL method offers the possibility of observing the behavior of the test object at its load limits, e.g., through stress and performance tests.

For HiL testing, the embedded system under test (SUT) is connected via its inputs and outputs to a HiL test bench, which models the system environment of the test object using simulated sensors, actuators, and mechanical and electrical components. The inputs of the test object are then stimulated with data from the environment model.

HiL tests are usually performed under real-time conditions. The management software for the HiL infrastructure is therefore often run on real-time capable hardware. There are various HiL hardware and software solutions from different manufacturers on the market. A widely used solution for HiL test equipment comes from NI (formerly National Instruments). NI offers the VeriStand software environment for managing HiL hardware components. This offers numerous control and management functions. VeriStand enables test engineers to configure I/O channels, integrate simulation models, log data, generate stimuli, and communicate with the hardware of the HiL system, for example.

In addition, VeriStand allows user-defined functionality to be added to the test environment. This is a great help, for example, in optimizing the creation of test case specifications.

A central front end for the test engine

The complexity, growing number of functions, and thus possible input and output signals of an average embedded system, such as an automotive control unit, leads to a high number of test cases, among other things.In order to master the enormous test scope of modern electronic systems, a high degree of continuous automation of the test process is essential. The basis for such test automation is the creation of test case specifications.

In VeriStand, test specifications can be created using programming and scripting languages. However, this requires the user to have certain programming skills and is relatively time-consuming. In order to provide a simple way to specify test cases for automated execution in a hardware-in-the-loop environment, it is advisable to integrate specialized tools into the test environment. Various tools from different manufacturers are available on the market for this purpose. In-house developments can also perform this function. ITPower Solutions has made its in-house test tool ContinoProva available for use in a HiL environment via a connection to NI VeriStand. The architecture of the tool used is, of course, important for this application.

The ContinoProva tool was originally designed for use in heterogeneous tool environments. It specializes in automating test execution and test evaluation. Thanks to its open client-server architecture, it can be used widely in almost all test environments and in every test phase. The tool abstracts from the user and programming interfaces of the test environment in which it is used and provides a uniform front end for the specification of tests and the control of connected hardware and software tools. Of course, this requires that connected tools have the appropriate APIs.

ContinoProva communicates with external tools via so-called services, which can call all relevant functions and methods of the corresponding tool via its programming interface (API) and receive its corresponding return values. Encapsulating communication in services enables use in different tool environments.