I don't even mind declaring variables all that much. I think a lot of it comes down to locality, as I've got all the "testing" code in the same piece of code, instead of in a totally separate test suite. So type declarations, design-by-contract, debug statements would be my first choice, and I actually often start out with these (or approximations thereof) even in more dynamic languages, refactoring some of those as unit tests later on. (In a similar vein, I don't usually start out with interfaces, abstract classes etc. - if possible not even with classes at all. Guess that makes me a spaghetti sorter.)

Granted, that's mostly for starting out. In an existing code base, especially a larger one, different rules apply. I don't believe in methodology panaceas.