DRY up first/last and hence make last benefit from the bugfix in first

activerecord/lib/active_record/associations/association_collection.rb

@@ -36,25 +36,12 @@ def find(*args)
         end
       end
 
-      # Fetches the first one using SQL if possible.
       def first(*args)
-        if fetch_first_or_last_using_find?(args)
-          scoped.first(*args)
-        else
-          load_target unless loaded?
-          args.shift if args.first.kind_of?(Hash) && args.first.empty?
-          @target.first(*args)
-        end
+        first_or_last(:first, *args)
       end
 
-      # Fetches the last one using SQL if possible.
       def last(*args)
-        if fetch_first_or_last_using_find?(args)
-          scoped.last(*args)
-        else
-          load_target unless loaded?
-          @target.last(*args)
-        end
+        first_or_last(:last, *args)
       end
 
       def to_ary
@@ -560,6 +547,17 @@ def find_by_scan(*args)
             load_target.select { |r| ids.include?(r.id) }
           end
         end
+
+        # Fetches the first/last using SQL if possible, otherwise from the target array.
+        def first_or_last(type, *args)
+          if fetch_first_or_last_using_find?(args)
+            scoped.send(type, *args)
+          else
+            load_target unless loaded?
+            args.shift if args.first.kind_of?(Hash) && args.first.empty?
+            @target.send(type, *args)
+          end
+        end
     end
   end
 end

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -86,10 +86,16 @@ def test_no_sql_should_be_fired_if_association_already_loaded
     Car.create(:name => 'honda')
     bulbs = Car.first.bulbs
     bulbs.inspect # to load all instances of bulbs
+
     assert_no_queries do
       bulbs.first()
       bulbs.first({})
     end
+
+    assert_no_queries do
+      bulbs.last()
+      bulbs.last({})
+    end
   end
 
   def test_create_resets_cached_counters