A boundary value analysis is defined as a software testing technique that uses the boundary values of equivalence classes as input to test cases. Black box testing uses boundary value analysis as one of the most commonly used case design techniques.  

In boundary value analysis, values at the boundaries are included in test cases. It is generally true that there are more errors at the boundaries of an input domain than in its center, which makes boundary value analysis an excellent method for generating test cases. In boundary value analysis, values at the boundaries are included in test cases. When the input lies within the boundary range, it is a positive test, but if it lies outside, it is a negative test. The values may include the maximum, the minimum, the inside edge, the outside edge, the typical value or the error value.

Example: Assume you're testing an input box accepting numbers from 1 to 20. As a result of boundary value analysis, we can divide test cases into three categories:

• The test data will be the same as the input boundaries of input: 1 and 20.


• Input values above the extreme edges: 2 and 21.


• Input values below the extreme edges: 0 and 19.

Therefore, the boundary values are 0, 1, 2, and 19, 20, 21.