Inherited methods are hidden in serializer

[dpogue]

Expected behavior vs actual behavior

When subclassing a serializer, the parent class's instance methods are not populated in the child class's instance method list, so _serializer_instance_method_defined? returns false.

This started breaking with commit a065bc2.

Steps to reproduce

class ParentSerializer < ActiveModel::Serializer
  attributes :$id

  define_method(:$id) do
    object.id
  end
end

class ChildSerializer < ParentSerializer
  attributes :name
end

Throws the following error:
undefined method '$id' for <Child:0x00...>

Environment

ActiveModelSerializers Version (commit ref if not on tag): 7acbb76

Output of ruby -e "puts RUBY_DESCRIPTION": ruby 2.1.5p273 (2014-11-13 revision 48405) [x86_64-darwin14.0]

OS Type & Version: OSX 10.11.4

Integrated application and version (e.g., Rails, Grape, etc): Rails

[bf4]

Oh interesting.

I can fix that, unless you're interested in helping out with a pr.

Also, curious, what are you using the define_method for? Could use an attribute with the key: option or just alias the id method

[dpogue]

In practice, I'm using URIs for identifiers, so define_method(:$id) returns scope.url_for(self). Ruby won't let you use def for a method starting with a $.

[bf4]

Should be fixed by #1661