Broken Tests in ActionPack

The ActionPack tests are borked. Unrelated tests affect each other. For proof, try removing the "unless defined?" clause around Customer in the beginning of actionpack/tests/controllers/render_test.rb. It is actually using the incompatible definition from new_render_test.rb because of the order in which the tests are performed. However, the order is different on other platforms, so the "unless defined?" is really only hiding the problem from most users.

I hate to be a bother, but this really needs attention. I'd gladly fix it if someone were to suggest how this particular issue should be fixed. It scares me that unrelated tests can influence each other's results. These are either poorly-written test files that break some fundamental rules of testing, or the test suite itself should be fixed to prevent this sort of thing from happening. Yes, we need to test our testing.

Here's my original ticket:

Please discuss.