Boundary Value Testing & Equivalence Partitions

            I was looking for some materials to supplement the work we are doing in Software Quality Assurance and Testing (CS-443) and I came across a nice article from ReQtest entitled What is Boundary Value Analysis and Equivalence Partitioning? I found this to be a good supplement to our in-class activity on boundary value testing, summarizing some of the key ideas. It helped me nail down the concepts and is a nice, short resource for me.

            The article begins describing boundary value analysis. It highlights it is focused on, well, the boundary values, as, “for the most part, errors are observed in the extreme ends of the input values.” This directly relates to the topics covered in class, but is limited as it is mostly focused on single inputs, rather than testing for multiple inputs like we did in class. The article then provides a couple example for an input domain of 1 to 100. The exact boundary values would be 1 and 100, just below boundary values would be 0 and 99, and just above boundary values would be 2 and 101. This seems similar to robust boundary value testing. However, the article doesn’t consider multiple inputs, so there is no noting of nominal inputs or the single fault assumption, or worst-case boundary value testing. Nonetheless, I find it is a concise way of summarizing normal boundary value testing.

            The article then goes on to describe equivalence partitioning, which is the division of, “test input data into a range of values and selecting one input value from each range.” This goes more towards describing the domain of input values and somewhat alludes to physical and arbitrary boundaries. These are not described within the article, but are worthy of noting. The example given is again in the 1 to 100 acceptable range. The article states that one valid input class is anywhere within the 1 to 100 range, another is any value below 1, and the last is any value above 100.

            Together, these two topics do well to sum up the different ranges of inputs for boundary value testing, with equivalence partitioning touching on a little bit of worst-case boundary value testing. Overall, I thought this was a worthwhile article and was helpful. I can see myself returning to it when I actually am writing tests. Boundary value testing is quite useful in many cases, so it’s a topic I’m happy and interesting in learning more about and practicing.  

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