Boundary Value Analysis
Boundary Value Analysis (BVA) is a black-box test technique that designs test cases using values at the edges of input or output partitions where defects are most likely to occur.
“A black-box test technique in which test cases are designed based on boundary values.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Boundary Value Analysis?
Boundary Value Analysis improves test effectiveness by focusing on minimum, maximum, and adjacent values instead of testing every possible input.
Why boundaries matter: Software defects frequently occur at the limits of allowed ranges due to comparison or validation errors.
Applying BVA: Testers identify each boundary and select values at, just below, and just above the limit depending on the chosen BVA approach.
Relationship to Equivalence Partitioning: BVA complements Equivalence Partitioning by concentrating on the edges of each partition.
Visual Example
Typical boundary layout (valid range in the middle)
Real World Example
A banking team is updating the daily transfer limit rules for personal accounts, including the exact minimum and maximum amounts a customer may send.
The risky part is not the middle of the range; it is the values sitting at, just below, and just above each limit. That is where Boundary value analysis becomes practical instead of theoretical.
The tester turns the rule into focused test data, checks the valid edges, and deliberately tries values just outside the allowed range to expose off-by-one and validation defects.
Because the team understands Boundary value analysis, they catch limit-handling defects before release instead of discovering them through failed customer transfers.
Practice Questions
Question 1
Which set BEST applies BVA for 0–100 inclusive?
Question 2
Which statement BEST describes BVA?
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