Maybe I shouldn't call it TDD camp, but the people that were prothletising TDD were also selling onion/DDD in C# world, so I just bunch those together, it's more about onion, layered architectures, testing at different layers and mocking them, etc.

While I consider TDD the wrong approach in 90% of scenarios, in dynamic languages it works out much better because the object model is so flexible you can mock just about anything trivially. In C# and Java it's just boilerplate on top of boilerplate.