# How does Boundary Value Analysis work?

In a flight reservation system, the number of available seats in each plane model is an input. A plane may have any positive number of available seats, up to the given capacity of the plane. Using Boundary Value analysis, a list of available – seat values were generated. Which of the following lists is correct?

A. 1, 2, capacity -1, capacity, capacity plus 1

B. 0, 1, capacity, capacity plus 1

C. 0, 1, 2, capacity plus 1, a very large number

D. 0, 1, 10, 100, capacity, capacity plus one

• You should do a proper search before asking homework level questions here. This should be answered with a simple google search Dec 15 '15 at 8:10

Option (B) will be correct answer.

``````(B) 0, 1, capacity, capacity plus 1
``````

Why? Let first understand BVA..

Boundary value analysis (BVA) is defined in Wikipedia as a software testing technique in which tests are designed to include representatives of boundary values in a range.

In your example, Seat numbers can range from 1 to capacity. So these will be 2 valid values lying on boundary of range. For invalid values, we will simply take value before to minimum valid value and value next to maximum valid value. As shown below:

``````       ... -2 -1  0 1 .........capacity  capacity+1 .....
------------------|-------------------|-------------------
invalid partition 1   valid partition   invalid partition 2
``````

So, the boundary values will be 0,1, capacity and capacity+1.

valid boundary values = 1, capacity

invalid boundary values = 0, capacity+1

Check this link for more examples and to get better understanding: http://www.softwaretestinghelp.com/what-is-boundary-value-analysis-and-equivalence-partitioning/

• Why there's no test case for capacity -1? Dec 15 '15 at 10:19
• Alsp this won't work if capacity is 0 Dec 15 '15 at 10:20
• @dzieciou, agree with your scenarios. But this answer is only within scope of 4 given options using BVA. It appears to be an MCQ. Dec 15 '15 at 11:01

B. 0, 1, capacity, capacity plus 1 is the correct answer. In BVA we consider valid as well as invalid values. The minimum number of seats that a person can book is 1 hence we will try to book something which is less than the minimum number and more than the maximum number. 0 is less than minimum number -Invalid partition 1 is a valid value so it is a valid partition capacity +1 is more than the max capacity hence again its an invalid partition. We have covered all the scenarios of BVA by giving all the valid and invalid inputs.

Boundary Analysis work

Example:Q In an Examination a candidate has to score minimum of 24 marks in order to clear the exam. The maximum that he can score is 40 marks. Identify the Valid Equivalence values if the student clears the exam.

a) 22,23,26

b) 21,39,40

c) 29,30,31

d) 0,15,22

Solution:

The classes will be as follows:

Class I: values < 24 => invalid class Class II: 24 to 40 => valid class Class III: values > 40 => invalid class

We have to identify Valid Equivalence values. Valid Equivalence values will be there in Valid Equivalence class. All the values should be in Class II. So answer is ‘C’