Acceptance Test-Driven Development / Behavior Driven Development involves a triad: the customer, developer, and tester. The power of three people working together can create a shared understanding expressed with descriptions of behavior that form acceptance tests. If the triad writes the tests together, the distinction between user acceptance tests and system tests is practically eliminated. The three roles of customer, developer, and tester may be played by different individuals or by the same individual with different focuses or a group of people taking on those perspectives.

The Triad

  • The customer who provides the requirements
  • The developer who implements the requirements
  • The tester who critically analyzes the requirements and the implementation


Here is a summary of ATDD/BDD benefits.   It's in the Given-When-Then format which is a popular way of expressing scenarios and tests.

Given current conditions like these:

  • No detailed requirements
  • Unclear business rules
  • Poorly defined acceptance criteria
  • Not enough testers
  • Defects hold up deployment
  • Development team not understanding business process

When Acceptance Test-Driven Development / Behavior Driven Development (ATDD/BDD) is added

Then you can get the following results:

  • Tests for details of requirements
  • Getting business rules right
  • Crisp visible story completion criteria
  • Tighter cross-functional team integration
  • Rework down from 60% to 20%
  • Workflows working first time


A Chinese proverb says, “There are many paths to the top of the mountain, but the view is always the same.” And many of the paths share the same trail for portions of the journey. Although acceptance testing has been around for a long time, it was reinvigorated by extreme programming . Its manifestations include ATDD as described in Lean-Agile Acceptance Test-Driven Development by Ken Pugh, example-driven development (EDD) by Brian Marick, behavior-driven development (BDD) by Dan North, story test-driven development (SDD) by Joshua Kerievsky of Industrial Logic, domain-driven design (DDD) by Eric Evans, and executable acceptance test-driven development (EATDD). All these share the common goal of producing high-quality software. They aid developers and testers in understanding the customer’s needs prior to implementation and customers being able to converse in their own domain language.

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Other Books on ATDD

TDD by Example: A Practical Guide to Acceptance Test-Driven Development by Markus Gärtner

Specification by Example: How Successful Teams Deliver the Right Software  by Gojko Adzic

Bridging the Communication Gap: Specification by Example and Agile Acceptance Testing Paperback by Gojko Adzic (Author)