Which black-box test technique focuses on designing test cases based on boundary values?

The focus of the black-box test technique that emphasizes designing test cases based on boundary values is indeed boundary value analysis. This approach is specifically tailored to identify errors at the edges of input ranges, where the likelihood of defects is often higher.

Boundary value analysis operates on the premise that errors frequently occur at the extremes of input values, as well as just outside of these boundaries. For example, if the input range is between 1 and 100, the technique would create test cases for values such as 1, 100, 0 (below the minimum), and 101 (above the maximum), capturing critical transitional points where issues may arise during application execution. This method enhances the probability of discovering defects related to input validation and processing.

In contrast, the other techniques serve different testing purposes. Equivalence partitioning divides input data into partitions that are expected to behave similarly, focusing on representative values rather than edge cases. Decision table testing is used for capturing combinations of inputs and their corresponding outputs, which is particularly beneficial for systems with numerous conditional paths. State transition testing evaluates the behavior of a system based on various states and transitions, primarily focusing on the sequence of inputs and their effects on system states. Each of these methods has its unique objectives and applications