What is BDD?

BDD is a way for software teams to work that closes the gap between business people and technical people by:

• Encouraging collaboration across roles to build shared understanding of the problem to be solved
• Working in rapid, small iterations to increase feedback and the flow of value
• Producing system documentation that is automatically checked against the system’s behaviour

We do this by focusing collaborative work around concrete, real-world examples that illustrate how we want the system to behave. We use those examples to guide us from concept through to implementation, in a process of continuous collaboration.

BDD and agile

We assume that your team are using some kind of agile methodology already, planning work in small increments of value like User Stories. BDD does not replace your existing agile process, it enhances it.

Think of BDD as a set of plugins for your existing process that will make your team more able to deliver on the promises of agile: timely, reliable releases of working software that meets your organisation’s evolving needs, requiring some maintenance effort and discipline.

Rapid iterations

We assume you would like to be able to respond quickly to feedback from your users, and do only the minimal work necessary to meet those needs.

BDD encourages working in rapid iterations, continuously breaking down your user’s problems into small pieces that can flow through your development process as quickly as possible.

Three practices

Essentially, day-to-day BDD activity is a three-step, iterative process:

1. First, take a small upcoming change to the system – a User Story – and talk about concrete examples of the new functionality to explore, discover and agree on the details of what’s expected to be done.
2. Next, document those examples in a way that can be automated, and check for agreement.
3. Finally, implement the behaviour described by each documented example, starting with an automated test to guide the development of the code.

The idea is to make each change small and iterate rapidly, moving back up a level each time you need more information. Each time you automate and implement a new example, you’ve added something valuable to your system, and you’re ready to respond to feedback.

We call these practices Discovery, Formulation, and Automation.