Merge pull request #6579 from amatsuda/null_relation_modulize

modulize AR::NullRelation

activerecord/lib/active_record/null_relation.rb

@@ -2,24 +2,24 @@
 
 module ActiveRecord
   # = Active Record Null Relation
-  class NullRelation < Relation
+  module NullRelation
     def exec_queries
       @records = []
     end
 
-    def pluck(column_name)
+    def pluck(_column_name)
       []
     end
 
-    def delete_all(conditions = nil)
+    def delete_all(_conditions = nil)
       0
     end
 
-    def update_all(updates, conditions = nil, options = {})
+    def update_all(_updates, _conditions = nil, _options = {})
       0
     end
 
-    def delete(id_or_array)
+    def delete(_id_or_array)
       0
     end
 
@@ -51,13 +51,12 @@ def count
       0
     end
 
-    def calculate(operation, column_name, options = {})
+    def calculate(_operation, _column_name, _options = {})
       nil
     end
 
-    def exists?(id = false)
+    def exists?(_id = false)
       false
     end
-
   end
-end
+end

activerecord/lib/active_record/relation/query_methods.rb

@@ -279,7 +279,7 @@ def lock!(locks = true)
     #   end
     #
     def none
-      NullRelation.new(@klass, @table)
+      scoped.extending(NullRelation)
     end
 
     def readonly(value = true)

activerecord/test/cases/relations_test.rb

@@ -226,7 +226,6 @@ def test_none
     assert_no_queries do
       assert_equal [], Developer.none
       assert_equal [], Developer.scoped.none
-      assert           Developer.none.is_a?(ActiveRecord::NullRelation)
     end
   end
 
@@ -236,6 +235,12 @@ def test_none_chainable
     end
   end
 
+  def test_none_chainable_to_existing_scope_extension_method
+    assert_no_queries do
+      assert_equal 1, Topic.anonymous_extension.none.one
+    end
+  end
+
   def test_none_chained_to_methods_firing_queries_straight_to_db
     assert_no_queries do
       assert_equal [],    Developer.none.pluck(:id) # => uses select_all