D3 vs TDD best practices [closed]

Question

Which one offers more advantages for a large software, say like Photoshop?

Also by TDD I don't mean just unit tests, because you can use unit tests in D3 too, just not the same way TDD does.

D3: Design Driven Development

TDD: Test-Driven Development

Answer 1

DDD = Domain Driven Design

TDD means that before you write any unit of behavior you have a test for this behavior and only this behavior. Only after these tests fail do you implement the behavior. In every incarnation that I've seen TDD has been on the level of a method or class - maybe a couple classes working together. The end result is that you get highly testable and hence very loosely coupled code. Ultimately though TDD is about creating code that can be tested.

DDD is a far more abstract philosophy and set of design patterns that addresses how to design a large, scalable, and maintainable system. Ultimately DDD is about creating a code eco-system that implicitly or explicitly captures important bits of domain knowledge.

So you see, they are certainly not mutually exclusive. Pretty much everyone I know who is knowledgeable in DDD is also a hard-core TDD enthusiast.

Answer 2

TDD is neither bottom-up nor writing tests before coding. TDD is about using tests to drive the development with the goal that the code is tested before delivery. It begins with ensuring that the user requirements are written in a form that makes automated user acceptance tests possible. It continues through integration and functional testing down to unit testing. Unit testing does form the lion's share in the end.

The reason why tests should be written first is because when a solution to a problem is considered (designed), you automatically have expectations what the solution should do. Any expectation can be expressed as a test, so why not immediately document the expectation and at the same time have an automated test for it to ensure the solution achieves that goal?

Answer 3

I also don't think they're mutually exclusive I think you can use TDD to get to DDD.