Why is design-by-contract not so popular compared to test-driven development?

Question

You may think this question is like this question asked on StackOverflow earlier. But I am trying to look at things differently.

In TDD, we write tests that include

Answer 1

I've used both in the past and found DBC-style less "intrusive". The driver for DBC may be regular application running. For Unit Tests you have to take care of setup because you expect (validate) some responses. For DBC you don't have to. Rules are written in data-independent manner, so no need to setup and mocking around.

More on my experiences with DBC/Python: http://blog.aplikacja.info/2012/04/classic-testing-vs-design-by-contract/