Extract Named and/or Unnamed Arguments from a Ruby Method (http://stackoverflow.com/questions/22026694/ruby-keyword-arugments-can-you-treat-all-of-the-keyword-arguments-as-a-hash)

argument_extraction_spec.rb

describe "Argument Extraction Experiment" do
  let(:experiment_class) do
    Class.new do
      def method_with_mixed_args(one, two = 2, three:, four: 4)
        extract_args(binding)
      end

      def method_with_named_args(one:, two: 2, three: 3)
        extract_named_args(binding)
      end

      def method_with_unnamed_args(one, two = 2, three = 3)
        extract_unnamed_args(binding)
      end

      private

      def extract_args(env, depth = 1)
        caller_param_names = method(caller_locations(depth).first.label).parameters
        caller_param_names.map do |(arg_type,arg_name)|
          { name: arg_name, value: eval(arg_name.to_s, env), type: arg_type }
        end
      end

      def extract_named_args(env)
        extract_args(env, 2).select {|arg| [:key, :keyreq].include?(arg[:type]) }
      end

      def extract_unnamed_args(env)
        extract_args(env, 2).select {|arg| [:opt, :req].include?(arg[:type]) }
      end
    end
  end

  describe "#method_with_mixed_args" do
    subject { experiment_class.new.method_with_mixed_args("uno", three: 3) }
    it "should return a list of the args with values and types" do
      expect(subject).to eq([
        { name: :one,    value: "uno", type: :req },
        { name: :two,    value: 2,     type: :opt },
        { name: :three,  value: 3,     type: :keyreq },
        { name: :four,   value: 4,     type: :key }
      ])
    end
  end

  describe "#method_with_named_args" do
    subject { experiment_class.new.method_with_named_args(one: "one", two: 4) }
    it "should return a list of the args with values and types" do
      expect(subject).to eq([
        { name: :one,    value: "one", type: :keyreq },
        { name: :two,    value: 4,     type: :key },
        { name: :three,  value: 3,     type: :key }
      ])
    end
  end

  describe "#method_with_unnamed_args" do
    subject { experiment_class.new.method_with_unnamed_args(2, 4, 6) }
    it "should return a list of the args with values and types" do
      expect(subject).to eq([
        { name: :one,    value: 2,  type: :req },
        { name: :two,    value: 4,  type: :opt },
        { name: :three,  value: 6,  type: :opt }
      ])
    end
  end
end

# $ rspec argument_extraction_spec.rb --format documentation
# Argument Extraction Experiment
#  #method_with_mixed_args
#    should return a list of the args with values and types
#  #method_with_named_args
#    should return a list of the args with values and types
#  #method_with_unnamed_args
#    should return a list of the args with values and types
#
# Finished in 0.00183 seconds (files took 0.09806 seconds to load)
# 3 examples, 0 failures