scaffold: yml files for tests are missing

ruby 1.9.3p286 (2012-10-12 revision 37165) [x86_64-darwin10.8.0]
rails 3.1.3

Probably it is my misunderstanding but doesn't scaffold generate
test/fixtures/model_name.yml file automatically?

Normally I use scaffold for creating many models, but test/fixtures
folder is empty.
Not mention I have certainly executed rake db:migrate command and the
application is working correctly as I intended.

Since the application is getting complicated, I need to run test
scripts. But I have now realized test/fixtures and test/functional are
empty.
Maybe I have set up the application wrong somehow.

Can you guess what went wrong?
or is there anyway to regenerate necessary files for tests?

Thanks

soichi