The fixture caching introduced with Rails 2 doesn't work if your project uses ActiveRecord::Base.table_name_prefix (or _suffix). You will get a NoMethodError with a stacktrace like this:
You have a nil object when you didn't expect it!
The error occurred while evaluating nil.table_name
proj/vendor/rails/activerecord/lib/active_record/fixtures.rb:1003:in `load_fixtures'
proj/vendor/rails/activerecord/lib/active_record/fixtures.rb:1003:in `each'
proj/vendor/rails/activerecord/lib/active_record/fixtures.rb:1003:in `load_fixtures'
proj/vendor/rails/activerecord/lib/active_record/fixtures.rb:941:in `setup'
...and so on.
The problem is that the fixtures are stored in the cache using the actual table name (i.e., with the prefix and/or suffix), but looked up using the fixture name (without the prefix or suffix).
A workaround is to use set_fixture_class, but since the table names all follow a pattern, this is not very DRY. A better solution would be to index the cache by the fixture name instead of the table name. Patch coming soon.
Rhett Sutphin
josh