Refactor Association into Field like everything else (#1897)

* Make assocations asserts easier to understand

* Refactor Association into Field like everything else

* Make assocation serializer/links/meta lazier

* Push association deeper into relationship

* Simplify association usage in relationships

* Better naming of reflection parent serializer

* Easier to read association method

test/adapter/json_api/relationship_test.rb

@@ -155,15 +155,17 @@ module ActiveModelSerializers
 
           serializable_resource_options = {} # adapter.instance_options
 
-          meta = test_options.delete(:meta)
-          options = test_options.delete(:options)
-          links = test_options.delete(:links)
+          options = test_options.delete(:options) || {}
+          options[:links] = test_options.delete(:links)
+          options[:meta] = test_options.delete(:meta)
           association_serializer = @serializer
           if association_serializer && association_serializer.object
             association_name = association_serializer.json_key.to_sym
-            association = ::ActiveModel::Serializer::Association.new(association_name, association_serializer, options, links, meta)
+            options[:serializer] = association_serializer
+            association = ::ActiveModel::Serializer::Association.new(association_name, options, nil)
           else
-            association = ::ActiveModel::Serializer::Association.new(:association_name_not_used, association, options, links, meta)
+            options[:serializer] = association
+            association = ::ActiveModel::Serializer::Association.new(:association_name_not_used, options, nil)
           end
 
           relationship = Relationship.new(parent_serializer, serializable_resource_options, association)

test/serializers/associations_test.rb

@@ -31,13 +31,13 @@ module ActiveModel
 
           case key
           when :posts
-            assert_equal({ include_data: true }, options)
+            assert_equal true, options.fetch(:include_data)
             assert_kind_of(ActiveModelSerializers.config.collection_serializer, serializer)
           when :bio
-            assert_equal({ include_data: true }, options)
+            assert_equal true, options.fetch(:include_data)
             assert_nil serializer
           when :roles
-            assert_equal({ include_data: true }, options)
+            assert_equal true, options.fetch(:include_data)
             assert_kind_of(ActiveModelSerializers.config.collection_serializer, serializer)
           else
             flunk "Unknown association: #{key}"
@@ -79,7 +79,7 @@ module ActiveModel
             flunk "Unknown association: #{key}"
           end
 
-          assert_equal({ include_data: true }, association.options)
+          assert_equal true, association.options.fetch(:include_data)
         end
       end
 
@@ -291,11 +291,23 @@ module ActiveModel
       end
 
       class InheritedSerializerTest < ActiveSupport::TestCase
+        class PostSerializer < ActiveModel::Serializer
+          belongs_to :author
+          has_many :comments
+          belongs_to :blog
+        end
+
         class InheritedPostSerializer < PostSerializer
           belongs_to :author, polymorphic: true
           has_many :comments, key: :reviews
         end
 
+        class AuthorSerializer < ActiveModel::Serializer
+          has_many :posts
+          has_many :roles
+          has_one :bio
+        end
+
         class InheritedAuthorSerializer < AuthorSerializer
           has_many :roles, polymorphic: true
           has_one :bio, polymorphic: true
@@ -333,9 +345,18 @@ module ActiveModel
         end
 
         test 'a serializer inheriting from another serializer can redefine belongs_to associations' do
-          expected = [:author, :comments, :blog].sort
-          result = (@inherited_post_associations - @post_associations).map(&:name).sort
-          assert_equal(result, expected)
+          assert_equal [:author, :comments, :blog], @post_associations.map(&:name)
+          assert_equal [:author, :comments, :blog, :comments], @inherited_post_associations.map(&:name)
+
+          refute @post_associations.detect { |assoc| assoc.name == :author }.options.key?(:polymorphic)
+          assert_equal true, @inherited_post_associations.detect { |assoc| assoc.name == :author }.options.fetch(:polymorphic)
+
+          refute @post_associations.detect { |assoc| assoc.name == :comments }.options.key?(:key)
+          original_comment_assoc, new_comments_assoc = @inherited_post_associations.select { |assoc| assoc.name == :comments }
+          refute original_comment_assoc.options.key?(:key)
+          assert_equal :reviews, new_comments_assoc.options.fetch(:key)
+
+          assert_equal @post_associations.detect { |assoc| assoc.name == :blog }, @inherited_post_associations.detect { |assoc| assoc.name == :blog }
         end
 
         test 'a serializer inheriting from another serializer can have an additional association with the same name but with different key' do