Acceptance test–driven development (ATDD) is a collaborative process where developers, testers and business representatives come together to work out requirements, perceive potential pitfalls and reduce the chance of errors before coding begins. ATDD is written from the perspective of the user and answers the question "Is the code doing what it's supposed to do?"
The first step in ATDD is to assemble all parties involved and hold a specification workshop. Once requirements are defined and clarified in the workshop, the testers can create automated tests from the specified criteria. Quality assurance (QA) testers work with developers in order to implement the first test and automate it. ATDD also makes unit testing easier to implement.
ATDD test format
ATDD tests usually adhere to the following format:
Given: A setup, specified state.
And (optional): Setup continued.
When: Trigger, an action or event happens.
Then: Verification. State has changed or output is produced.
An example using the ATDD format:
Given: Movie listed on catalog of video streaming app.
And: User is a paid subscriber.
When: User selects movie to watch from app catalog.
Then: Movie is streamed for user.
Benefits of ATDD
ATDD brings everyone involved in development together to discuss the criteria around which an app is built. Clarity on requirements helps reduce wasted efforts and understanding how a business expects things to function can reduce recoding and errors. ATDD can often be beneficial for developers using Agile.
Even in cases where testing is not automated or the testers have little knowledge of coding, there is still value in clarifying business conditions and logic. All teams can benefit from collaboration with business experts and early discussion of how to test so that necessary requirements are filled. The end result of ATDD is a better, more reliable application.
ATDD vs. TDD
While ATDD concentrates on collaboration and testing for user functionality, test-driven development (TDD) follows more of a developer-focused approach. TDD focuses on running and automating unit tests and is easier to implement. Both ATDD and TDD aim to reduce unnecessary code and developer resources, while creating comprehensive requirements and testing continuously to make sure a product meets user expectations.