# Boundary value analysis ###### tags: `Black Box Testing Tech` `ISTQB` `Software Testing` `SQA` - One kind of mistakes that programmers make is that errors tend to cluster around boundaries. [^1] - the number of times a program loop is executed - the exact point at which a loop should stop executing - This works well with **the equivalence partitioning idea** because partitions must have boundaries. - Boundary values - **The valid boundary values** are the lowest and the highest value on the inside of a valid partition. - **The non-valid boundary values** are the first values as close as you can get according to the **the precision** that has been applied to the partition when you step outside the partition at the top and bottom end. - The number of values to be analysis: - **2 values at each boundary**: the valid boundary value itself and its non-valid boundary values. - **3 values at each boundary**: the boundary value itself and one value either side of the boundary (documented in BS 7925-2) [^1]: [Defect clustering General testing principles](https://hackmd.io/YUmBtNF9QBq_ULk9u0PF4w#General-testing-principles)