Test Case Generation Method for Increasing Software Reliability in Safety-Critical Embedded Systems

Abstract

Finite-state machines (FSMs) and the W method have been widely used in software testing. However, the W method fails to detect post-processing errors in the implementation under test (IUT) because it ends testing when it encounters a previously visited state. To alleviate this issue, we propose an enhanced fault-detection W method. The proposed method does not stop the test, even if it has reached a previously visited state; it continues to test and check the points that the W method misses. Through various case studies, we demonstrated software testing using the W method and the proposed method. From the results, it can be inferred that the proposed method can more explicitly determine the consistency between design and implementation, and it is a better option for testing larger software. Unfortunately, the testing time of the proposed method is approximately 1.4 times longer than that of the W method because of the added paths. However, our method is more appropriate than the W method for software testing in safety-critical systems, even if this method is time consuming. This is because the error-free characteristics of a safety-critical system are more important than anything else. As a result, our method can be used to increase software reliability in safety-critical embedded systems.