Black Box Testing Technique : Boundary value analysis

Black Box Testing Technique

If I would like to execute testing a software (testing web or windows application), I start with thinking about how to select the test cases. If I have no idea about software's internal algorithm and cannot cover all combinations of input values and preconditions for a module of software because of resource constraint (Time or manpower), I will use Black Box Testing Technique to design the input values.

Boundary value analysis

Boundary value analysis is a software testing technique that selects the input data which represents boundary values. These data includes both boundary and each side of boundary which should be in the smallest increment. 

Example
I would like to test withdrawal on ATM system. The maximum amount is $500 and minimum amount is $1.

Find boundary value:

1. Maximum value is $500
2. Minimum value is $1

Find each side of boundary value

1. $501 and $499 for "Maximum value is $500" case
2. $2 and $0 for "Maximum value is $1" case

The final list of input values are 

1. $501, $499 and $500
2. $2, $0 and $1

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Now you can design and execute testing a software (testing web or windows application) by using Boundary value analysis testing technique. 

Let's find the pairwise testing (All-pairs testing) technique in the next article.

Posted in: Test Design Technique