Add NullAdapater

lib/active_model/serializer/adapter.rb

@@ -3,6 +3,7 @@ module ActiveModel
     class Adapter
       extend ActiveSupport::Autoload
       autoload :SimpleAdapter
+      autoload :NullAdapter
 
       def initialize(serializer)
         @attributes = serializer.attributes

lib/active_model/serializer/adapter/null_adapter.rb

@@ -0,0 +1,15 @@
+module ActiveModel
+  class Serializer
+    class Adapter
+      class NullAdapter < Adapter
+        def serializable_hash(options = {})
+          {}
+        end
+
+        def to_json(options = {})
+          serializable_hash.to_json
+        end
+      end
+    end
+  end
+end

test/adapter/null_adapter_test.rb

@@ -0,0 +1,21 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class Adapter
+      class NullAdapterTest < Minitest::Test
+        def setup
+          profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+          serializer = ProfileSerializer.new(profile)
+
+          @adapter = NullAdapter.new(serializer)
+        end
+
+        def test_it_returns_empty_json
+          assert_equal('{}', @adapter.to_json)
+        end
+      end
+    end
+  end
+end
+

test/adapter_test.rb

@@ -15,7 +15,7 @@ module ActiveModel
         end
       end
 
-      def test_serializable_hash_is_abstract_method
+      def test_to_json_is_abstract_method
         assert_raises(NotImplementedError) do
           @adapter.to_json(only: [:name])
         end