Add Model#attributes helper; make test attributes explicit

test/adapter/attributes_test.rb

@@ -3,11 +3,8 @@ require 'test_helper'
 module ActiveModelSerializers
   module Adapter
     class AttributesTest < ActiveSupport::TestCase
-      class Person
-        include ActiveModel::Model
-        include ActiveModel::Serialization
-
-        attr_accessor :first_name, :last_name
+      class Person < ActiveModelSerializers::Model
+        attributes :first_name, :last_name
       end
 
       class PersonSerializer < ActiveModel::Serializer

test/adapter/json_api/fields_test.rb

@@ -4,9 +4,17 @@ module ActiveModelSerializers
   module Adapter
     class JsonApi
       class FieldsTest < ActiveSupport::TestCase
-        class Post < ::Model; end
-        class Author < ::Model; end
-        class Comment < ::Model; end
+        class Post < ::Model
+          attributes :title, :body
+          associations :author, :comments
+        end
+        class Author < ::Model
+          attributes :name, :birthday
+        end
+        class Comment < ::Model
+          attributes :body
+          associations :author, :post
+        end
 
         class PostSerializer < ActiveModel::Serializer
           type 'posts'

test/adapter/json_api/include_data_if_sideloaded_test.rb

@@ -5,7 +5,9 @@ module ActiveModel
     module Adapter
       class JsonApi
         class IncludeParamTest < ActiveSupport::TestCase
-          IncludeParamAuthor = Class.new(::Model)
+          IncludeParamAuthor = Class.new(::Model) do
+            associations :tags, :posts
+          end
 
           class CustomCommentLoader
             def all

test/adapter/json_api/linked_test.rb

@@ -1,6 +1,6 @@
 require 'test_helper'
 
-class NestedPost < ::Model; end
+class NestedPost < ::Model; associations :nested_posts end
 class NestedPostSerializer < ActiveModel::Serializer
   has_many :nested_posts
 end
@@ -301,8 +301,8 @@ module ActiveModelSerializers
       end
 
       class NoDuplicatesTest < ActiveSupport::TestCase
-        class Post < ::Model; end
-        class Author < ::Model; end
+        class Post < ::Model; associations :author end
+        class Author < ::Model; associations :posts, :roles, :bio end
 
         class PostSerializer < ActiveModel::Serializer
           type 'posts'

test/adapter/json_api/links_test.rb

@@ -4,7 +4,7 @@ module ActiveModelSerializers
   module Adapter
     class JsonApi
       class LinksTest < ActiveSupport::TestCase
-        class LinkAuthor < ::Model; end
+        class LinkAuthor < ::Model; associations :posts end
         class LinkAuthorSerializer < ActiveModel::Serializer
           link :self do
             href "http://example.com/link_author/#{object.id}"

test/adapter/json_api/relationship_test.rb

@@ -384,7 +384,7 @@ module ActiveModelSerializers
 
         def new_model(model_attributes)
           Class.new(ActiveModelSerializers::Model) do
-            attr_accessor(*model_attributes.keys)
+            attributes(*model_attributes.keys)
 
             def self.name
               'TestModel'

test/adapter/json_api/transform_test.rb

@@ -4,9 +4,17 @@ module ActiveModelSerializers
   module Adapter
     class JsonApi
       class KeyCaseTest < ActiveSupport::TestCase
-        class Post < ::Model; end
-        class Author < ::Model; end
-        class Comment < ::Model; end
+        class Post < ::Model
+          attributes :title, :body, :publish_at
+          associations :author, :comments
+        end
+        class Author < ::Model
+          attributes :first_name, :last_name
+        end
+        class Comment < ::Model
+          attributes :body
+          associations :author, :post
+        end
 
         class PostSerializer < ActiveModel::Serializer
           type 'posts'