@tgxworld I'm fine with global state modifications inside `setup` as long as every test depends on it. We should not modify more state than absolutely necessary. That's why I favor helper methods within the test method.

In this particular case it's good to modify `min_cost` in `setup` / `teardown` because it's for performance reasons. However tests that do rely on an explicit value of `min_cost` should still assign it to be explicit.