This tutorial demonstrates the development of a small system using test-driven development and supporting technologies. The system will comprise a handful of Java classes that exemplify typical components found in enterprise applications, including domain objects, a service layer, and gateways.

The tutorial presents two complementary approaches to TDD: state-based testing and interaction-based testing. Both approaches will be discussed in depth during the development of the system, and benefits of each approach will be highlighted and contrasted. The tutorial also covers common trade-offs and edge case, e.g. how to deal with testing private methods and when not to use dynamic mocks but hand-crafted stub objects. The implementation will use modern technologies such as JUnit 4, Hamcrest, and Mockito.

Attendees will gain an understanding of how proper use of test-driven development fosters good design; through decoupling and interface discovery for example. Attendees will also gather a nice catalogue of the most commonly used patterns used in conjunction with test-driven development.