What is defined as an input or output value on the edge of an equivalence partition?

The concept of a boundary value relates specifically to testing in the context of equivalence partitioning. In this testing strategy, equivalence classes are identified as subsets of input or output values that are believed to be processed the same way by the software. Within each equivalence class, certain values can be deemed more critical, specifically those that lie at the boundaries of these classes.

Boundary values are used because they are points where the behavior of the system is expected to change. This can include the lowest and highest values that the system can accept or produce. Testing at these edge points is essential because many errors occur at the boundaries, making them particularly valuable in identifying defects. Therefore, defining an input or output value on the edge of an equivalence partition highlights the significance of boundary values in effective test case design.

The other choices refer to concepts that, while related to testing, do not specifically denote the input or output value at the edge of an equivalence partition. Selective input typically refers to deliberately chosen inputs for specific testing objectives, edge case can refer to scenarios that are on the edge of normal operation but doesn't specifically highlight the input or output value on the edge of a partition, and equivalence class is a broader term encompassing the entire set of values