Dummy Object の作り方

dummy_object.rb

require 'minitest/autorun'

class ModuleTest < Minitest::Test
  def test_module_eval
    debugger = Object.new
    debugger.class.module_eval do
      define_method(:debug) {|s| %(debug: #{s}) }
    end
    assert_equal 'debug: Hello', debugger.debug("Hello")
  end

  def test_meta_class
    debugger = Object.new
    class << debugger
      define_method(:debug) {|s| %(debug: #{s}) }
    end
    assert_equal 'debug: Hello', debugger.debug("Hello")
  end

  # def (debugger = ()).debug(s); %(debug: #{s}) end
  # はトリッキー？
  def test_method
    debugger = Object.new
    def debugger.debug(s)
      %(debug: #{s})
    end
    assert_equal 'debug: Hello', debugger.debug("Hello")
  end
end