I read an article in Software Test and Performance magazine about the topic “Fuzzing”. This was the first time I had heard this term. However recently I heard some of my team’s tester talking about the issues involved with fuzzing. So I thought I would write about this as well.

Fuzzing is a negative software testing method. That means you do not test for whether the system works correctly with correct inputs. Instead fuzzing concentrates on things such as inputting malformed data to an application. It also involves attempts to defeat system security. This used to be a hacking technique. Now it has been formalized as a testing methodology.

Requirements themselves can be written in a positive and negative form. That is, requirements usually dictate what the software must do. However some requirements also define the desired system behavior by describing also what the system shall not do.

A way to perform fuzzing is to start with a test case. Then you can modify the test data and rerun the test. The more general realm of testing is robustness testing. This is where you test how the system behaves when there are invalid inputs. One such form of robustness testing is fuzzing. The main purpose of fuzzing is to identify security problems in the system.

When I was with some of our team’s testers, I heard them talking about their negative testing. I did not drop the “fuzzing” buzzword with them. However it was good to see that they are addressing modern topics in the test world.