Simple parse to find all constants in a Ruby file

const_parse.rb

require 'test_helper'
require 'ripper'


# see http://svenfuchs.com/2009/7/5/using-ruby-1-9-ripper
# Only finds contants which are referenced or defined via class
# does not find constants which are defined inline i.e. X=true
class ConstParser < Struct.new(:source)
  def consts
    consts = []
    walker = -> x do
      x.each do |token, *remainder|
        # Will not find classed defined like X = Struct.new do; end
        if token == :const_path_ref || token == :const_ref
          # cheating here and just getting the string portion,
          # this might be a bit fragile
          consts << remainder.flatten.select {|p| p.is_a?(String)}.join("::")
        else
          walker.call(remainder) if remainder.is_a?(Array)
          walker.call(token) if token.is_a?(Array)
        end
      end
    end

    walker.call(Ripper.sexp(File.read(source)))
    consts
  end
end

describe ConstParser do
  let(:p) { ConstParser.new 'app/schedules/pjm/dispatch_lambda_job.rb' }
  it { assert_equal [], p.consts }
end