TDD vs. BDD: What’s the Difference? (Complete Comparison)

Test-Driven Development (TDD) and Behavior-Driven Development (BDD) are two distinct software development methodologies that are often mistaken for each other due to their overlapping objectives but different focuses and approaches. TDD emphasizes writing tests before code implementation to ensure comprehensive coverage and correctness, following a cycle of writing a failing test, making it pass, and then refactoring. It is developer-centric and aims to improve software design and quality. BDD, on the other hand, extends TDD by incorporating business requirements and domain language to ensure that software behavior aligns with user expectations, fostering collaboration among developers, testers, and non-technical stakeholders. It uses scenarios written in natural language that everyone involved can understand, following a process of discovery, formulation, and automation. Although TDD and BDD have different goals, they can coexist in a development cycle, with TDD focusing on component correctness and BDD ensuring alignment with user stories and business outcomes.