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            Boundary Value Analysis  

Boundary value analysis is one of the most daily based used technique for black box testing .

It is a test case design method for black box testing also  As all we know the most of errors occurs at boundary of the input values. This is one of the techniques used to find the mistakes in the boundaries of input values rather than the center of the input value range.

Boundary Value Analysis is the next step of the Equivalence class in which all test cases are arranged at the edges of the Equivalence class

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Let us take an example to explain this:

                Suppose we have software application which obtain the input value text box ranging from 1 to 1000, in this case we have invalid and valid inputs:

Invalid Input	Valid Input	Invalid Input
0 – less	1 – 1000	1001 – above

Here are the Test cases for input box accepting numbers using Boundary value analysis:

Min value – 1	0
Min Value	1
Min value + 1	2
Normal Value	1 – 1000
Max value – 1	999
Max value	1000
Max value +1	1001

Examples 1 :

Suppose you have very crucial tool at office, accepts valid User Name and Password field to work on that tool, and accepts minimum 8 characters and maximum 12 characters. Valid range 8-12, Invalid range 7 or less than 7 and Invalid range 13 or more than 13.

Write Test Cases for Valid partition value, Invalid partition value and exact boundary value.

•       Test Cases 1: Consider password length less than 8.

•       Test Cases 2: Consider password of length exactly 8.

•       Test Cases 3: Consider password of length between 9 and 11.

•       Test Cases 4: Consider password of length exactly 12.

•       Test Cases 5: Consider password of length more than 12.

Example 2 :

Test cases for the application whose input box accepts numbers between 1-1000. Valid range 1-1000, Invalid range 0 and Invalid range 1001 or more.

Write Test Cases for Valid partition value, Invalid partition value and exact boundary value.

•       Test Cases 1: Consider test data exactly as the input boundaries of input field  i.e. values 1   and 1000.

•       Test Cases 2: Consider test data with values just below the extreme edges of input field i.e. values 0 and 999.

Test Cases 3: Consider test data with values just above the extreme edges of input domain i.e. values 2 and 1001.