Restore has_one to generator

per #822 since it was readded in #725

Author: bf4

lib/generators/serializer/templates/serializer.rb

@@ -3,6 +3,6 @@ class <%= class_name %>Serializer < <%= parent_class_name %>
   attributes <%= attributes_names.map(&:inspect).join(", ") %>
 end
 <% association_names.each do |attribute| -%>
-  attribute :<%= attribute %>
+  has_one :<%= attribute %>
 <% end -%>
 <% end -%>

test/generators/serializer_generator_test.rb

@@ -38,7 +38,7 @@ def test_generates_attributes_and_associations
     run_generator
     assert_file "app/serializers/account_serializer.rb" do |serializer|
       assert_match(/^  attributes :id, :name, :description$/, serializer)
-      assert_match(/^  attribute :business$/, serializer)
+      assert_match(/^  has_one :business$/, serializer)
     end
   end