Industrial Scale Passive Testing with T-EARS

Passive testing continuously observes the system or system execution logs without any interference or instrumentation to test diverse combinations of functions, resulting in a more thorough evaluation over time. However, reaching a working solution to passive testing is not without challenges. While there have been some efforts to extract information from system requirements to create passive test cases, to our knowledge, no such efforts are mature enough to be applied in a real, industrial safety-critical context. Our passive testing approach uses the Timed Easy Approach to Requirements Syntax (T-EARS) specification language and its accompanying tool-chain. This study reports challenges and solutions to introducing system-level passive testing for a vehicular safety-critical system through industrial data analysis, including 116 safety-related requirements. Our results show that passive testing using the T-EARS language and its tool-chain can be used for system-level testing in an industrial setting for 64% of the studied requirements. We identified several sources of false positive results and show how to tune test cases to reduce such false positives systematically. Finally, we show the requirement coverage achieved by a manual test session and that passive testing using T-EARS can find a set of injected faults that are considered hard to find with other test techniques.