ATA: ISTQB Advanced Level Test Analyst

Boundary value analysis explicitly targets a single boundary by choosing values immediately on either side of that boundary (the boundary value itself and its nearest neighbor, e.g., n and n+1 for the smallest measurable unit); a test set built around one such adjacent pair isolates and exercises exactly one boundary, whereas sets composed of round, widely separated values instead sample multiple distinct boundaries or equivalence-partition midpoints rather than a single one.