Add tests for virtual_delegate has_one

spec/lib/extensions/ar_virtual_spec.rb

@@ -622,11 +622,15 @@ def self.connection
 
             include VirtualFields
           end
+
+          class CompSys < ComputerSystem
+          end
         end
 
         after do
           TestOtherClass.remove_connection
           Object.send(:remove_const, :TestOtherClass)
+          Object.send(:remove_const, :CompSys)
         end
 
         it "delegates to another table" do
@@ -644,6 +648,15 @@ def self.connection
           sql = TestOtherClass.all.select(:id, :ocol1, TestOtherClass.arel_attribute(:col1).as("x")).to_sql
           expect(sql).to match(/"test_classes"."col1"/i)
         end
+
+        it "delegates has_one relationships with limit 1" do
+          CompSys.virtual_delegate :name, :to => :operating_system, :prefix => true
+          comp_sys = CompSys.create!
+          OperatingSystem.create(:name => "foo", :computer_system_id => comp_sys.id)
+          OperatingSystem.create(:name => "bar", :computer_system_id => comp_sys.id)
+          query = CompSys.all.select(:id, :operating_system_name)
+          expect(query.map(&:operating_system_name)).to match_array(["foo"])
+        end
       end
     end