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Boundary Value Selection Rule

publish date: 2026/06/17 05:49:38.016680 UTC

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A good rule of thumb for selecting test cases from equivalence partitions is to choose values at the boundaries and near the midpoint. Why are boundary values particularly important?

Boundary values always produce the fastest execution path through the code

Boundary values are the easiest to compute and document automatically

Testing guidelines require at least three tests per partition boundary

Designers and programmers tend to overlook atypical boundary values, and program failures often occur there

Correct Answer

Designers and programmers tend to overlook atypical boundary values, and program failures often occur there

Explanation

Designers and programmers tend to consider typical values when developing a system. Boundary values are often atypical (e.g., zero may behave differently from other non-negative numbers) and are therefore sometimes overlooked. Program failures often occur when processing these atypical values, making boundary testing especially valuable.

Reference

Software Engineering, Ian Sommerville, 10th edition

Quizzes you can take where this question appears

Choosing Unit Test Cases - Partition Testing