Better AMS Model attributes interface

test/action_controller/serialization_scope_name_test.rb

@@ -2,16 +2,16 @@ require 'test_helper'
 
 module SerializationScopeTesting
   class User < ActiveModelSerializers::Model
-    attr_accessor :id, :name, :admin
+    attributes :id, :name, :admin
     def admin?
       admin
     end
   end
   class Comment < ActiveModelSerializers::Model
-    attr_accessor :id, :body
+    attributes :id, :body
   end
   class Post < ActiveModelSerializers::Model
-    attr_accessor :id, :title, :body, :comments
+    attributes :id, :title, :body, :comments
   end
   class PostSerializer < ActiveModel::Serializer
     attributes :id, :title, :body, :comments

test/active_model_serializers/model_test.rb

@@ -10,7 +10,7 @@ module ActiveModelSerializers
 
     def test_initialization_with_string_keys
       klass = Class.new(ActiveModelSerializers::Model) do
-        attr_accessor :key
+        attributes :key
       end
       value = 'value'
 

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/cache_test.rb

@@ -244,7 +244,7 @@ module ActiveModelSerializers
     # rubocop:disable Metrics/AbcSize
     def test_a_serializer_rendered_by_two_adapter_returns_differently_fetch_attributes
       Object.const_set(:Alert, Class.new(ActiveModelSerializers::Model) do
-        attr_accessor :id, :status, :resource, :started_at, :ended_at, :updated_at, :created_at
+        attributes :id, :status, :resource, :started_at, :ended_at, :updated_at, :created_at
       end)
       Object.const_set(:UncachedAlertSerializer, Class.new(ActiveModel::Serializer) do
         attributes :id, :status, :resource, :started_at, :ended_at, :updated_at, :created_at

test/fixtures/poro.rb

@@ -31,7 +31,7 @@ end
 #   model.validate!            # => ["cannot be nil"]
 #   model.errors.full_messages # => ["name cannot be nil"]
 class ModelWithErrors < ::ActiveModelSerializers::Model
-  attr_accessor :name
+  attributes :name
 end
 
 class Profile < Model

test/serializers/read_attribute_for_serialization_test.rb

@@ -5,10 +5,10 @@ module ActiveModel
     class ReadAttributeForSerializationTest < ActiveSupport::TestCase
       # https://github.com/rails-api/active_model_serializers/issues/1653
       class Parent < ActiveModelSerializers::Model
-        attr_accessor :id
+        attributes :id
       end
       class Child < Parent
-        attr_accessor :name
+        attributes :name
       end
       class ParentSerializer < ActiveModel::Serializer
         attributes :$id
@@ -30,7 +30,7 @@ module ActiveModel
 
       # https://github.com/rails-api/active_model_serializers/issues/1658
       class ErrorResponse < ActiveModelSerializers::Model
-        attr_accessor :error
+        attributes :error
       end
       class ApplicationSerializer < ActiveModel::Serializer
         attributes :status

test/serializers/serialization_test.rb

@@ -2,10 +2,10 @@ module ActiveModel
   class Serializer
     class SerializationTest < ActiveSupport::TestCase
       class Blog < ActiveModelSerializers::Model
-        attr_accessor :id, :name, :authors
+        attributes :id, :name, :authors
       end
       class Author < ActiveModelSerializers::Model
-        attr_accessor :id, :name
+        attributes :id, :name
       end
       class BlogSerializer < ActiveModel::Serializer
         attributes :id