Professional C++

Chapter 19. Becoming Adept at Testing

A programmer has overcome a major hurdle in her career when she realizes that testing is a part of the software development process. Bugs are not an occasional occurrence. They are found in every project of significant size. A good quality-assurance (QA) team is invaluable, but the full burden of testing cannot be placed on QA alone. Your responsibility as a programmer is to write code that works and tests to prove its correctness.

A distinction is often made between white box testing, in which the tester is aware of the inner workings of the program, and black box testing, which tests the program's functionality without concern for its implementation. Both forms of testing are important to professional-quality projects. Black box testing is the most fundamental approach because it typically models the behavior of a user. For example, a black box test can examine interface components like buttons. If the tester clicks the button and nothing happens, there is obviously a bug in the program.

Black box testing cannot cover everything. Modern programs are too large to employ a simulation of clicking every button, providing every kind of input, and performing all combinations of commands. White box testing is necessary because it is easier to ensure test coverage when tests are written at the object or subsystem level. White box tests are often easier to write and automate than black box tests. This chapter focuses on topics that would generally be ...