[Tech] Integrate Tests as a Language Featuere?

The blog of Cedric Beust (author of TestNG and captured by Google) is always an interesting read.

His last posting discusses the question if generic test features should be included into the language:

http://beust.com/weblog/archives/000522.html

He mentioned an interesting D feature. Personally I think a tighter language integration is useful for small projects. Nevertheless it should be easy to switch to the best testing tools (as TestNG) in bigger projects.

What do you think?