White-Box Functional Testing

“What is the heart but a spring, and the nerves but so many strings, and the joints but so many wheels, giving motion to the whole body?”

- Thomas Hobbes

The last chapter described the key approaches to black-box testing. By looking at the external behavior of a feature, thoroughly defined by the feature specification, you can test its primary functionality and ensure it meets all the requirements.

Unlike black-box testing, where the implementation of a feature is unknown, white-box testing lets a tester understand the workings of the code and design test cases to exercise it all. You’ll now cast aside the naivety that was initially so useful to find surprises and unexpected behavior. Here, you need as much knowledge as possible to understand how and why the implementation works – the springs and joints of your particular application.

This will let you see dependencies that may not have been obvious: areas of code...