Coverage and fault detection of the output-uniqueness test selection criteria

This paper studies the whitebox coverage and fault detection achieved by Output Uniqueness, a newly proposed blackbox test criterion, using 6 web applications. We find that output uniqueness exhibits average correlation coefficients of 0.85, 0.83 and 0.97 with statement, branch and path coverage respectively. More interestingly, output uniqueness finds 92% of the real faults found by branch coverage (and a further 47% that remained undetected by such whitebox techniques). These results suggest that output uniqueness may provide a useful surrogate when whitebox techniques are inapplicable and an effective complement where they are.