Test synthesis: from wishful thinking to reality

A few years ago, most people understood "test synthesis" to be a two-step process: first, analysis of the functionality of a design to exploit its inbuilt structural testability and second, to modify functionality for enhanced structural testability. Well, that was truly wishful thinking. The reality today, however, is that test synthesis now means adding test logic purely for the purposes of structural testability. Furthermore, as we get closer to the nuts and bolts of the process, it is interesting to note how the synthesis of test logic in a design becomes mostly a challenge to satisfy the target software tools (ATPG) and ATE requirements instead of addressing the enhancement of fault coverage.