DIY fixtures - forget factory_girl and their ilk. Usually in lib/fixtures/fixtures.rb because they can be used in rake tasks and other not-specifically-test places. Add requires in test_helper and then in whatever rake tasks or scripts use them.
fixture = self.new(opts)
class CustomerFixture < BaseFixture
Customer.new(opts.reverse_merge(:name => Faker::Name.name))
“seed.rb is broken” <- if you don't use this much, then that can happen. If you re-use DIY Fixtures in tests, seeding and exploratory testing - everywhere. Less likely to break.