RecordCollections
Don't expose ActiveRecord::Relations, expose RecordCollections!
Testing what is or isn't in scope of a ActiveRecord::Relation is REALLY hard. RecordCollections make it easy (so long as you use decently sized scopes).
Usage
Controllers
def index
@users = RecordCollection.new(User)
.limit_by(User.active)
.and(User.first_name("Jane"))
.and(User.over_21)
end
RSpec
subject(:users) { assigns[:users] }
it { should be_limited_by?(User.active) }
it { should be_limited_by?(User.first_name("Jane")) } # Yes, it even works with arguments to the scope
it { should be_limited_by?(User.over_21) }
it { should_not be_limited_by?(User.under_50) } # Maybe there are some scopes you definitely don't want