Boundary value analysis in automatic white-box test generation

White-box testing is an effective technique for generating test cases to provide high coverage for programs. We usually select several execution paths using some strategy, and generate a corresponding test case that follows each path. Each execution path corresponds to an input subspace bounded by constraints. Extreme values in these subspaces are very likely to trigger failures since the constraints bounding input subspaces may be faulty. In this paper, we propose a new way of defining the boundaries of comparison predicates in white-box testing, and apply constrained combinatorial testing to cover these boundaries with reduced number of test cases. Our approach can guarantee to cover all possible boundaries for each selected execution path, thus achieving high fault coverage for boundary faults, while the original structural coverage is still preserved.