Loading different fixtures?

I’m starting to write some rather intricate billing logic, the test data
for which will almost certainly overwhelm my standard set of test
fixtures, leading to a test maintenance nightmare. I’d like to be able
to specify that some test classes load their fixtures from a different
location, but I can’t seem to get it to work.

I did see this post from last December:

However, installing the engines plugin as mentioned there didn’t get me
the expected behavior (perhaps it was taken back out again?).
Similarly, the patch from ticket 1911 is against 0.13.1; I’d be
surprised if it worked on 1.1…

I’ve also tried the following:

class RolldownTest < Test::Unit::TestCase
self.fixture_path =
fixtures :authorizations, :timecards #, etc

This works when I just run the test as a standalone, but it utterly
hoses all other tests when I run rake.

Any other suggestions?