has_one returns arrays with roots pluralized

lib/active_model/serializer.rb

@@ -164,7 +164,12 @@ end
            association.serializer_class <= ArraySerializer)
         associated_data.map { |elem| association.build_serializer(elem).serializable_hash }
       else
-        association.build_serializer(associated_data).serializable_object
+        serializable_obj = association.build_serializer(associated_data).serializable_object
+        if !(association.serializer_class && association.serializer_class <= ArraySerializer)
+          serializable_obj = [serializable_obj]
+          serializable_obj.compact!
+        end
+        serializable_obj
       end
     end
 

lib/active_model/serializer/associations.rb

@@ -17,7 +17,6 @@ module ActiveModel
         @embed_in_root = options.fetch(:embed_in_root) { options.fetch(:include) { CONFIG.embed_in_root } }
         @embed_key     = options[:embed_key] || :id
         @key           = options[:key]
-        @embedded_key  = options[:root] || name
 
         self.serializer_class = @options[:serializer]
       end
@@ -43,16 +42,18 @@ module ActiveModel
       end
 
       class HasOne < Association
-        def initialize(*args)
+        def initialize(name, *args)
           super
-          @key  ||= "#{name}_id"
+          @embedded_key = "#{@options[:root] || name}".pluralize
+          @key ||= "#{name}_id"
         end
       end
 
       class HasMany < Association
-        def initialize(*args)
+        def initialize(name, *args)
           super
-          @key ||= "#{name.singularize}_ids"
+          @embedded_key = @options[:root] || name
+          @key ||= "#{name.to_s.singularize}_ids"
         end
       end
     end