Get core exts

monkey.rb

module Monkey
  extend self

  MODULE_NAME = Module.instance_method(:name)
  MODULE_SINGLETON_CLASS_P = Module.instance_method(:singleton_class?)
  MODULE_SINGLETON_CLASS = Module.instance_method(:singleton_class)
  MODULE_INSTANCE_METHODS = Module.instance_method(:instance_methods)
  MODULE_INSTANCE_METHOD = Module.instance_method(:instance_method)
  CLASS_ATTACHED_OBJECT = Class.instance_method(:attached_object) rescue nil
  IS_A = Object.instance_method(:is_a?)

  def diff
    clean = clean_env
    dirty = dirty_env

    clean.each do |mod_key, methods|
      mod, singleton_p = mod_key
      d = dirty[mod_key]

      methods.each do |method_name, clean_info|
        dirty_info = d[method_name]

        if clean_info[:source_location] != dirty_info[:source_location]
          puts "#{mod}#{singleton_p ? '.singleton_class' : ''}##{method_name} has changed"
          puts "  clean: #{clean_info[:source_location]}"
          puts "  dirty: #{dirty_info[:source_location]}"
        end
      end

      d.each do |method_name, dirty_info|
        next if methods.key?(method_name)

        puts "#{mod}#{singleton_p ? '.singleton_class' : ''}##{method_name} has been added"
        puts "  dirty: #{dirty_info[:source_location]}"
      end
    end
  end

  def clean_env
    with_unbundled_env do
      Marshal.load(`ruby --disable-gems -r #{File.expand_path(__FILE__)} -e 'puts Marshal.dump(Monkey.collect)'`)
    end
  end

  def dirty_env
    collect
  end

  def collect
    h = {}
    modules.each do |m|
      next if ARGF.class == m

      singleton_p = MODULE_SINGLETON_CLASS_P.bind_call(m)
      if MODULE_NAME.bind_call(m) && !singleton_p
        mod_key = [m, false]
      elsif singleton_p && (a = attached_object(m)) && IS_A.bind_call(a, Class) && MODULE_NAME.bind_call(a)
        mod_key = [a, true]
      else
        next
      end
      next if Monkey == mod_key[0]

      h[mod_key] = {}
      MODULE_INSTANCE_METHODS.bind_call(m).each do |method_name|
        method = MODULE_INSTANCE_METHOD.bind_call(m, method_name)
        h[mod_key][method_name] = {
          source_location: method.source_location,
        }
      end
    end
    h
  end

  def attached_object(klass)
    return CLASS_ATTACHED_OBJECT.bind_call(klass) if CLASS_ATTACHED_OBJECT

    modules.find do |m|
      IS_A.bind_call(m, Class) && MODULE_SINGLETON_CLASS.bind_call(m) == klass
    end
  end

  def modules
    @modules ||= ObjectSpace.each_object(Module).to_a
  end

  def with_unbundled_env(&block)
    if defined?(::Bundler)
      Bundler.with_unbundled_env(&block)
    else
      block.call
    end
  end
end

Monkey.diff if defined?(::Gem)

Requirement

No --disable-gems

Example

$ ruby -r YOUR_ENVIRONMENT -r ./monkey.rb

# For Rails
$ bin/rails r path/to/monkey.rb