Pass scope through to associations via @lastobelus

Closes #433

lib/active_model/serializer.rb

@@ -156,7 +156,7 @@ end
     end
 
     def serialize(association, object)
-      association.build_serializer(object).serializable_object
+      association.build_serializer(object, scope: scope).serializable_object
     end
 
     def serialize_ids(association)

lib/active_model/serializer/associations.rb

@@ -34,6 +34,17 @@ module ActiveModel
         @embed_objects = embed == :object || embed == :objects
       end
 
+      def build_serializer(object, options = {})
+        @serializer_class.new(object, options.merge(@options))
+      end
+
+      private
+
+      def use_array_serializer!
+        @options.merge!(each_serializer: @serializer_class)
+        @serializer_class = ArraySerializer
+      end
+
       class HasOne < Association
         def initialize(name, *args)
           super
@@ -41,13 +52,14 @@ module ActiveModel
           @key ||= "#{name}_id"
         end
 
-        def build_serializer(object)
+        def build_serializer(object, options = {})
           if object.respond_to?(:to_ary)
-            @options.merge!(each_serializer: @serializer_class)
-            @serializer_class = ArraySerializer
+            use_array_serializer!
+          else
+            @serializer_class ||= Serializer.serializer_for(object) || DefaultSerializer
           end
-          @serializer_class ||= Serializer.serializer_for(object) || DefaultSerializer
-          @serializer_class.new(object, @options)
+
+          super
         end
       end
 
@@ -58,13 +70,14 @@ module ActiveModel
           @key ||= "#{name.to_s.singularize}_ids"
         end
 
-        def build_serializer(object)
+        def build_serializer(object, options = {})
           if @serializer_class && !(@serializer_class <= ArraySerializer)
-            @options.merge!(each_serializer: @serializer_class)
-            @serializer_class = ArraySerializer
+            use_array_serializer!
+          else
+            @serializer_class ||= ArraySerializer
           end
-          @serializer_class ||= ArraySerializer
-          @serializer_class.new(object, @options)
+
+          super
         end
       end
     end

test/unit/active_model/serializer/scope_test.rb

@@ -17,5 +17,33 @@ module ActiveModel
         'user'
       end
     end
+
+    class NestedScopeTest < ActiveModel::TestCase
+      def setup
+        @association = UserSerializer._associations[:profile]
+        @old_association = @association.dup
+        @user = User.new({ name: 'Name 1', email: 'mail@server.com', gender: 'M' })
+        @user_serializer = UserSerializer.new(@user, scope: 'user')
+      end
+
+      def teardown
+        UserSerializer._associations[:profile] = @old_association
+      end
+
+      def test_scope_passed_through
+        @association.serializer_class = Class.new(ActiveModel::Serializer) do
+          def name
+            scope
+          end
+
+          attributes :name
+        end
+
+        assert_equal({
+          name: 'Name 1', email: 'mail@server.com', profile: { name: 'user' }
+        }, @user_serializer.serializable_hash)
+      end
+    end
+
   end
 end