01TDD in one paragraph
Write a failing test that describes the behaviour you want. Write the minimum code to make it pass. Refactor. Repeat. The point is design feedback — if writing the test is awkward, the code probably will be too.
02BDD in one paragraph
Describe behaviour as concrete examples in business-readable language ("Given a logged-in user, when they click logout, then they see the login page"). Engineers, QA, and product all read the same examples. The point is shared understanding before code is written.
03How they relate
- TDD is a developer discipline at the unit level
- BDD is a collaboration practice at the feature/behaviour level
- Both encourage writing tests early; they differ in audience and granularity
04When BDD pays off
If your team has friction between engineers, QA, and product on what "done" means, BDD examples become the shared spec. If you're a small all-engineer team that already aligns easily, the BDD ceremony may be overkill.
05Related
- Acceptance criteria vs test case
- Compare TestOrchestrator to Xray (Xray is BDD-first)
- Shift-left testing
06Frequently asked questions
Are BDD and TDD competing approaches?
Not really. Many teams use both — TDD for low-level design at the unit level, BDD for collaboration between engineers, QA, and product on high-level behaviour.
Do you need Cucumber/Gherkin to do BDD?
No. Gherkin (Given/When/Then) is one notation. The discipline — talking through behaviour examples before coding — is what matters.