I see. In this case I agree with the solution provided by @zuhao . The tests that do rely on an specific value of `min_cost` should set it inside the test methods. The ones that don't care inherit the setup to speed tests up. We should:

* store the original value of `min_cost` in setup and assign it back in `teardown`. (`@original_min_cost = ...`). This will get rid of hardcoded flags.
* use a descriptive comment to document the assignment in `setup` (that it is for performance reasons only).