Why are boundary values needed in testing?

Boundary value analysis is used to check the system's behavior at the edge conditions of the allowable input range. It is effective because errors often occur at the "edges" of ranges.

Reasons for use:

• Detecting errors at the "edges": The probability of errors is higher at boundary values than in the middle of the range.
• Reducing the number of test cases: Instead of testing all values in the range, it is enough to test only the boundary values and one or two values inside.
• Efficiency: The BVA method, combined with equivalence classes, covers a significant number of errors at lower costs.
• Standard approach: It is one of the main test design methods.

For example, if a field accepts values from 1 to 100, the boundary values will be 1, 2, 99, 100. Additionally, values outside the range are checked: 0 and 101.

Testing boundary values helps ensure that the system correctly handles minimum, maximum, and adjacent values.