test_case files in rails components

Question

I noticed there are a bunch of test_case.rb files delivered in the rails components:

• ./actionmailer-2.3.5/lib/action_mailer/test_case.rb
• ./actionpack-2.3.5/lib/action_controller/test_case.rb
• ./actionpack-2.3.5/lib/action_view/test_case.rb
• ./activerecord-2.3.5/lib/active_record/test_case.rb
• ./activesupport-2.3.5/lib/active_support/test_case.rb

I am wondering how to execute these files. I cant seem to figure out how to do it?