How the builder/director patterns and the use of chained method calls helped us vastly improve our Java unit tests by making them more reliable, easier to write, and easier to merge. Our test engineers now use the same infrastructure, allowing them to write "smoke" tests even faster (and they run faster, as well).
As a by-product, the infrastructure helped our sales and demo teams create complex sample data very easily.
This session assumes that you're already familiar with writing JUnit tests.