Testing your Boundaries

Boundary testing is a technique that “involves evaluating data based on boundary values… such as minimums and maximums.” It involves testing the lower and upper limits of a domain of inputs, as well as values just inside and outside those limits. This technique helps improve software quality by detecting defects early in the development process, which ultimately saves time and resources. This is due to the fact that “the number of defects at the boundaries of an input domain tends to be higher than in other areas of the domain.” 

Going back to how it saves time and resources, it helps developers choose more efficient test cases, which cuts down on time and how much they have to do, especially with large sets of data and number of inputs to consider. Furthermore, this technique “allows for a lot of uniformity and the test cases are much smaller” meaning that it can be automated. This would save more time, possibly result in less errors than if a person were to write the test cases, and allow for developers to put their focus on other tests or somewhere else, resulting in increased productivity. 

Boundary testing involves determining the input value range, which is whatever values the system accepts. Values inside that range are valid while those outside are invalid. Test cases are then created based on the values at the extreme ends, end values, and values just before and after the end values. For example, with a range of 0 to 100, we test values less than 0 (-50), greater than 100 (150), values around and at 0 and 100 (-1, 1, 99, 101). 

Another example the article shares is one that allows users to create a password. The password has to be 5 digits meaning that the range is 10000 at minimum and 99999 at maximum. Any combination of numbers is valid as long as it is 5 digits long, meaning that 4 digit long and 6 digit long passwords are outside the range and are invalid. 

Boundary testing seems like a very useful testing technique with very little downsides. It’s a black-box testing technique which usually means that testers don’t need extensive knowledge of coding, computer science, or the system at hand. It also seems very easy to do as long as all the necessary knowledge for testing is provided. Seeing as how it can also be easily automated, it may be more efficient to focus on more complex or time-consuming testing techniques while this test is running in the background or on the backburner.

https://www.indeed.com/career-advice/career-development/what-is-boundary-testing