Dynamic White-Box Testing Versus Debugging

It's important not to confuse dynamic white-box testing with debugging. If you've done some programming, you've probably spent many hours debugging code that you've written. The two techniques may appear similar because they both involve dealing with software bugs and looking at the code, but they're very different in their goals (see Figure 7.2).

Figure 7.2. Dynamic white-box testing and debugging have different goals but they do overlap in the middle.

The goal of dynamic white-box testing is to find bugs. The goal of debugging is to fix them. They do overlap, however, in the area of isolating where and why the bug occurs. You'll learn more about this in Chapter 19, "Reporting What You Find," but for now, think of the overlap this way. As a software tester, you should narrow down the problem to the simplest test case that demonstrates the bug. If it's white-box testing, that could even include information about what lines of code look suspicious. The programmer who does the debugging picks the process up from there, determines exactly what is causing the bug, and attempts to fix it.

NOTE

If you're performing this low-level testing, you will use many of the same tools that programmers use. If the program is compiled, you will use the same compiler but possibly with different settings to enable better error detection. You will likely use a code-level debugger to single-step through the program, watch variables, set break conditions, and so on. You may also write your own programs to test separate code modules given to you to validate.