Static White-Box Testing: Examining the Design and Code

Remember the definitions of static testing and white-box testing from Chapter 4? Static testing refers to testing something that isn't runningexamining and reviewing it.

White-box (or clear-box) testing implies having access to the code, being able to see it and review it.

Static white-box testing is the process of carefully and methodically reviewing the software design, architecture, or code for bugs without executing it. It's sometimes referred to as structural analysis.

The obvious reason to perform static white-box testing is to find bugs early and to find bugs that would be difficult to uncover or isolate with dynamic black-box testing. Having a team of testers concentrate their efforts on the design of the software at this early stage of development is highly cost effective.

A side benefit of performing static white-box testing is that it gives the team's black-box testers ideas for test cases to apply when they receive the software for testing. They may not necessarily understand the details of the code, but by listening to the review comments they can identify feature areas that sound troublesome or bug-prone.

NOTE

Development teams vary in who has the responsibility for static white-box testing. In some teams the programmers are the ones who organize and run the reviews, inviting the software testers as independent observers. In other teams the software testers are the ones who perform this task, asking the programmer who wrote the code and a couple of his peers to assist in the reviews. Ultimately, either approach can work. It's up to the development team to choose what works best for them.

The unfortunate thing about static white-box testing is that it's not always done. Many teams have the misconception that it's too time-consuming, too costly, or not productive. All of these are untruecompared to the alternative of testing, finding, and even not finding bugs at the back end of the project. The problem lies in the perception that a programmer's job is to write lines of code and that any task that takes away from his efficiency of churning out those lines is slowing down the process.

Fortunately, the tide is changing. Many companies are realizing the benefits of testing early and are hiring and training their programmers and testers to perform white-box testing. It's not rocket science (unless you're designing rockets), but getting started requires knowing a few basic techniques. If you're interested in taking it further, the opportunities are huge.