Incorporating Code Coverage in the Reliability Estimation for Fault-Tolerant Software

Mei-Hwa Chen, Michael R. Lyu and W. Eric Wong


The correlation between code coverage and the reliability of a single-version software has been an active subject studied by many researchers. However, the correlation between code coverage and reliability for fault-tolerant software has never been explored. Existing reliability and dependability models on fault tolerant software are based on approaches where software components are treated as black boxes. No coverage measurement or structural information was considered. We propose a technique that uses coverage measures in reliability estimation for fault tolerant programs, particularly N-version software. This technique exploits both coverage and time measures collected during testing phases for the individual program versions and the N-version software system for reliability prediction. The application of this technique on the single-version software was presented in our previous research. In this paper we extend this technique and apply it on the N-version programs. The results obtained from both the simulation experiment and the experiment conducted on an industrial project demonstrate that our technique significantly reduces the hazard of reliability overestimation for both single-version and multi-version fault tolerant software systems.