[radanskoric]

In theory you're 100% right, a true unit test is completely isolated from the rest of the system and than a lot of the problems disappear.

In reality, that is also not free. It imposes some restrictions on the code. Sometimes being pragmatic, backing off from the ideal leads to faster development and quicker deliver of value to the users. Rails is big on these pragmatic tradeoffs. The important thing is that we know when and why we're making the tradeoff.

Usually I go with Rails defaults and usually it's not a problem. Sometimes, when the code is especially complex and perhaps on the critical path, I turn up the purity dial and go down the road you describe exactly for the benefits you describe.

But when I decide that sticking to the defaults the is right tradeoff I want to get the most of it and use Fixtures (or Factories) in the optimal way.