[Deprecate] Resource#attributes is now deprecated

`select` is a preferred way.

Author: okuramasafumi

lib/alba/resource.rb

@@ -217,6 +217,8 @@ def attributes_to_hash(obj, hash)
 
       # This is default behavior for getting attributes for serialization
       # Override this method to filter certain attributes
+      #
+      # @deprecated in favor of `select`
       def attributes
         @_attributes
       end
@@ -328,6 +330,8 @@ def method_added(method_name) # rubocop:disable Metrics/MethodLength
           private(:serializable_hash_for_collection)
           alias_method :serializable_hash, :deprecated_serializable_hash
           alias_method :to_h, :deprecated_serializable_hash
+        when :attributes
+          warn 'Overriding `attributes` is deprecated, use `select` instead.', category: :deprecated, uplevel: 1
         when :_setup # noop
         else
           _resource_methods << method_name.to_sym

test/resource_test.rb

@@ -157,4 +157,19 @@ def collection_converter
   def test_deprecated_collection_converter
     assert_equal [@foo], DeprecatedConverterCollectionResource.new([@foo]).as_json
   end
+
+  def test_deprecated_attributes
+    assert_output('', /Overriding `attributes` is deprecated, use `select` instead./) do
+      Class.new do
+        include Alba::Resource
+        attributes :id
+
+        private
+
+        def attributes # rubocop:disable Lint/UselessMethodDefinition
+          super
+        end
+      end
+    end
+  end
 end