Fix sort order on ActiveRecord >= 5. re issue elastic#546 (elastic#831)

Author: jazzytomato

elasticsearch-model/lib/elasticsearch/model/adapters/active_record.rb

@@ -56,7 +56,10 @@ def order(*args)
             # Redefine the `to_a` method to the original one
             #
             sql_records.instance_exec do
-              define_singleton_method(:to_a) do
+              ar_records_method_name = :to_a
+              ar_records_method_name = :records if defined?(::ActiveRecord) && ::ActiveRecord::VERSION::MAJOR >= 5
+
+              define_singleton_method(ar_records_method_name) do
                 if defined?(::ActiveRecord) && ::ActiveRecord::VERSION::MAJOR >= 4
                   self.load
                 else

elasticsearch-model/test/integration/active_record_basic_test.rb

@@ -223,8 +223,10 @@ def as_indexed_json(options = {})
 
           if defined?(::ActiveRecord) && ::ActiveRecord::VERSION::MAJOR >= 4
             assert_equal 'Testing Coding', response.records.order(title: :desc).first.title
+            assert_equal 'Testing Coding', response.records.order(title: :desc)[0].title
           else
             assert_equal 'Testing Coding', response.records.order('title DESC').first.title
+            assert_equal 'Testing Coding', response.records.order('title DESC')[0].title
           end
         end