DDT is a highly methodical approach to testing, allowing you to know when you’ve finished – i.e. when you’ve written enough tests to cover the design and the requirements. It helps you to “zoom in” and write algorithmic tests to cover intensive or mission‐critical sections of code, and to know when it’s safe to “zoom out” and write fewer tests for boilerplate or less critical code.
In this Article, Doug extends the concept of DDT for hardware/software systems, allowing SysML‐based designs to be tested in a highly rigorous, systematic way. It’s still Design Driven Testing, but now the design elements that need to be tested include all of the “four pillars of SysML”, whereas DDT for software focuses on testing behavior.


