Selectivity of data-flow and control-flow path criteria

A given path-selection criterion is more selective than another such criterion with respect to some testing goal if it never requires more, and sometimes requires fewer, test paths to achieve that goal. The author presents canonical forms of control-flow and data-flow path selection criteria and demonstrates that, for some simple testing goals, the data-flow criteria as a general class are more selective than the control-flow criteria. It is shown, however, that this result does not hold for general testing goals, a limitation that appears to stem directly from the practice of defining data-flow criteria on the computation history contributing to a single result.<>