Behavior-driven development

Behavior-driven development (BDD) is an agile process designed to keep the focus on stakeholder value throughout the whole project. The premise of BDD is that the requirement has to be written in a way that everyone, be it the business representative, analyst, developer, tester, manager, and so on, understands it. The key is to have a unique set of artifacts that are understood and used by everyone—a collection of user stories. Stories are written by the whole team and used as both requirements and executable test cases. It is a way to perform TDD with a clarity that cannot be accomplished with unit testing. It is a way to describe and test functionality in (almost) natural language and make it runnable and repeatable.

A story is composed of scenarios. Each scenario represents a concise behavioral use case and is written in natural language using steps. Steps are a sequence of the preconditions, events, and outcomes of a scenario. Each step must start with the...