Behavior-driven Development
Behavior-Driven Development (BDD) is a collaborative development approach that uses examples written in business language to describe expected system behavior before implementation.
“A collaborative approach to development in which the team is focusing on delivering expected behavior of a component or system for the customer, which forms the basis for testing.”
(Definition reproduced from the ISTQB Glossary. Copyright belongs to ISTQB.)
View the complete ISTQB GlossaryWhat is Behavior-driven Development?
BDD encourages developers, testers, and business stakeholders to define software behavior together using scenarios that are easy for both technical and non-technical people to understand.
Shared language: BDD uses a common vocabulary that improves communication across the team.
Given-When-Then: Scenarios are commonly written using the Given-When-Then format.
Testing value: Executable scenarios help validate requirements and prevent misunderstandings.
Real World Example
A healthcare scheduling team is building a feature that lets patients book follow-up appointments after a consultation.
Developers, testers, clinicians, and product owners may all believe they understand the request while imagining different rules. Behavior-driven development gives the team a shared way to confirm intent.
The tester turns clinical and business expectations into concrete examples, such as eligible appointment windows, unavailable doctors, and messages shown when no slot is open.
The team prevents late rework because Behavior-driven development makes expected behavior testable before the feature is treated as finished.
Practice Questions
Question 1
Which statement BEST characterizes BDD?
Question 2
Which practice MOST supports BDD outcomes?
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