Bdd

Behavior-Driven Development (BDD) is a software engineering approach that extends Test-Driven Development by focusing on the observable behavior of a system for its end users. It emphasizes collaboration among developers, testers, and non-technical stakeholders to define software requirements in terms of user-visible behaviors.

Central to BDD is the use of ubiquitous language and concrete examples, typically written as features and scenarios. Scenarios are described using Given-When-Then steps to illustrate context, actions, and expected outcomes. The scenarios serve as acceptance criteria and living documentation.

The process usually begins with discovery and specification sessions, followed by writing feature files in human-readable form and then implementing automated tests that execute the scenarios. Tools such as Cucumber, SpecFlow, and Behave connect natural-language-like steps to code, enabling automated verification and integration into CI pipelines.

Benefits include improved alignment between business and technical teams, clearer acceptance criteria, and up-to-date documentation. Risks include brittle scenarios, overemphasis on automation at the expense of conversation, or excessive detail that narrows design.

History: Coined by Dan North in the early 2000s, BDD arose from TDD practices to make software behavior understandable to non-developers.