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.

ICONIX has collaborated with Sparx Systems to produce a uniquely powerful set of capabilities for driving testing from Enterprise Architect UML and SysML models.    By combining the functionality of Sparx's structured scenario editor and that of the Agile/ICONIX add-in, it's now possible to automatically generate test cases at multiple levels of abstraction.   These include two levels of developer testing, including automatic generation of unit test code for JUnit, NUnit and FlexUnit, and two levels of acceptance/QA testing, including generation of test cases for Requirements, and scenario-based testing using a "use case thread expander" which automatically generates test scripts covering all permutations of sunny-day/rainy-day scenarios.

We've published our approach in a book called Design Driven Testing (DDT), which I co-authored with Matt Stephens, and we proved our concepts on a real, commercially available product, an interactive mapping system built with ESRI's ArcGIS Server geospatial engine, and in commercial use on a travel website, VResorts.com.

The attached presentation, from the recent ESRI Developer Summit, presents the design of the hotel mapping application, and discusses bugs that were detected and fixed before product release following the DDT approach.