Requirements can be of any granularity

The seven-step approach I propose works for requirements of any granularity. Here, we applied it in a specification that could be implemented by a single method. However, nothing prevents you from using it with larger requirements that involve many classes. Traditionally, specification-based testing techniques focus on black-box testing: that is, testing an entire program or feature, rather than unit-testing specific components. I argue that these ideas also make sense at the unit level.

When we discuss larger tests (integration testing), we will also look at how to devise test cases for sets of classes or components. The approach is the same: reflect on the inputs and their expected outputs, divide the domain space, and create test cases. You can generalize the technique discussed here to tests at any level.