One of the most significant ways of ensuring that an application is reliable and efficient before deployment is through software testing. One of the most powerful functional testing techniques that focuses on testing the boundary cases of a system is Boundary Value Analysis (BVA). Boundary Value Analysis finds potential defects that are apt to show themselves on input partition boundaries.
What is Boundary Value Analysis?
Boundary Value Analysis is a black-box testing method which tests the boundary values of valid and invalid partitions. Instead of testing all the possible values, the testers focus on minimum, maximum, and edge-case values, as these are the most error-prone. This is because defects often occur at the extremities of the input ranges rather than at any point within the range.
For example, if a system accepts values between 18 and 56, instead of testing all the values, testers would test the below-mentioned values:
Valid boundary values: 18, 19, 37, 55, 56
Invalid boundary values: 17 (below minimum) and 57 (above maximum)
By running these primary test cases, the testers can easily determine boundary-related faults without unnecessary repetition of in-between value testing.
Implementing BVA: A Real-World Example
To represent BVA through an example, let us take a system processing dates under the following constraints:
Day: 1 to 31
Month: 1 to 12
Year: 1900 to 2000
Under Single Fault Assumption, where one of the variables is tested while others are at nominal values, test cases like below can be written:
Boundary value checking for years (e.g., 1900, 1960, 2000)
Boundary value checking for days (e.g., 1, 31, invalid cases like 32)
Checking boundary values for months (i.e., 1, 12)
By limiting test cases to boundary values, we are able to have maximum test coverage with minimum test effort.
Equivalence Partitioning and BVA together
Another helpful technique is combining BVA and Equivalence Partitioning (EP) together. EP divides input data into equivalent partitions where every equivalence class is expected to behave in the same way. By using these techniques together, testers can reduce the number of test cases but still maintain complete coverage.
For instance, if a system would only accept passwords of 6 to 10 characters long, test cases can be:
0-5 characters: Not accepted
6-10 characters: Accepted
11-14 characters: Not accepted
This mix makes the testing more efficient, especially when using more than one variable.
Limitations of BVA
Although BVA is strong, it does face some limitations:
It works well when the system contains properly defined numeric input ranges.
It has no regard for functional dependencies of variables.
It may not be equally effective on free-form languages like COBOL, which has more flexible input processing.
Conclusion
Boundary Value Analysis is one very important test method that can help testers define most probable fault sites of a system. Merged with Equivalence Partitioning, it has highest test effectiveness at the maximum elimination of test case replication and minimum complete loss of test coverage. In as much as BVA isn’t a “catch-all”, yet it represents an essential technique of software provision quality and dependability.
Personal Reflection
Learning Boundary Value Analysis has helped me understand more about software testing and how it makes the software reliable. It has shown me that by focusing on boundary values, defects can be detected with higher efficiency without generating surplus test cases. It is a very practical approach to apply in real-world scenarios, such as form validation and number input testing, where boundary-related errors are likely to be found. In the future, I will include BVA in my testing approach to offer more test coverage in software projects that I undertake.
Citation
Geeks for Geeks. (n.d.). Software Testing – Boundary Value Analysis. Retrieved from https://www.geeksforgeeks.org/software-testing-boundary-value-analysis/
From the blog CS@Worcester – Maria Delia by Maria Delia and used with permission of the author. All other rights reserved by the author.