A definition of the number of detections for faults with single tests in a compact scan-based test set

Abstract

Test quality metrics that use the numbers of detections of target faults are based on the premise that increasing the number of tests for a fault increases the likelihood of detecting defects around the site of the fault. This paper describes a new definition of the number of detections for faults that have only one test in a given test set. Such faults are prevalent in compact test sets. For a fault with a single test, metrics based on the number of detections yield the same value, one, for any test. The new definition associates different numbers of detections with different tests for the fault by considering the number of distinct test cubes that a test contains. It thus provides a target for the generation of a single test with a higher quality for the fault. The effectiveness of the definition is demonstrated by modifying a compact test set to increase the numbers of detections of single stuck-at faults with single tests, and comparing a bridging fault coverage of the test set before and after the modification.