Usually Behaviour driven development is focused on the business behaviour of your code: the “why” behind the code. The focus is usually on the intent rather than process. It supports a team-centric (especially cross-functional) workflow. BDD works really well when a developer and either the agile product owner or a business analyst sit down together and write the pending specifications:
Ideally, both parties can refer to the list of current system behaviours to see if this new feature will break existing features. This way quality comes first and the entire product is understood which decreases the defect entry into the development related to requirements or functionality of the system.
Test Driven Development is a proven practice in which developers are finding critical in order to deliver software that is both sustainable and high quality. TDD is tool that helps you design, it's not about the tests.
Approaches like TDD/BDD are used to understand the requirements clearly without any ambiguities and help developers to write tests in a way that makes code execution successful. These methods enable testers to think of solutions using a bottom up approach that helps prevention of defects in the later stages. This approach also helps clarify any ambiguities in the requirements early on in the software development lifecycle, before coding actually begins.
With an increased level of understanding of the features and requirements, developers know what exactly needs to be coded, as also what needs to be included or excluded in the code, thereby preventing leakage of defects into the code in the later phases of development lifecycle. The mindset and ability to focus on producing quality product with minimum to no defects from inception/upstream process is enabled by these methods that complement the shift left approach.The frequently tested code has lesser defects and enables faster delivery of working software to the clients.
A seamless implementation of both approaches identifies defects early on in the SDLC process, reduce risks, and reduce cost of rework which is a significant cost in software development process. TDD/BDD helps align the mind-set to the left focussing on quality from concept-to-cash for building the right product with the right intent in the best possible way.
The BDD/TDD practices enable the following: