The relationship between test coverage and reliability

In this paper, we model the relation between testing e ort, coverage and reliability. We present a logarithmic model that relates testing e ort to test coverage (block, branch, c-use or p-use). The model is based on the hypothesis that the enumerables (like branches or blocks) for any coverage measure have di erent detectability, just like defects have di erent detectability. This model allows us to relate a test coverage measure directly with defect coverage. Data sets for programs with real defects are used to validate the model. The results are consistent with the known inclusion relationships among block, branch and p-use coverage measures. We show how defect density controls time to next failure. The model can eliminate the variables like test application strategy from consideration. It is suitable for high reliability applications where automatic (or manual) test generation is used to cover enumerables which have not yet been tested.