What are the downsides using random values in Unit Testing?

Question

I\'m talking about a large scales system, with many servers and non deterministic input in high capacity. When i say non deterministic i\'m talking about messages that are s

Answer 1

I believe that generating random input values can be a reliable testing technique when used together with equivalence partitioning. This means that, if you partition your input space and then randomly pick values from an equivalence class, then you are fine: same coverage (any of them, including statement, branch, all-uses etc). This under the assumption that your equivalence partitioning procedure is sound. Also, I would recommend boundary value analysis to be paired with equivalence partitioning and randomly generated inputs.

Finally, I would also recommend considering the TYPE of defects you want to detect: some testing techniques address specific types of defects, which might be hardly (and just by chance) detected by other techniques. An example: deadlock conditions.

In conclusion, I believe that generating random values is not a bad practice, in particular in some systems (e.g. web applications), but it only addresses a subset of existing defects (like any other technique) and one should be aware of that, so to complement his/her quality assurance process with the adequate set of activities.