---
# System prepended metadata

title: Boundary value analysis
tags: [ISTQB, SQA, Software Testing, Black Box Testing Tech]

---

# 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)