Rewrite block source with instance eval

fail.rb

require 'rubygems'
require 'method_source'

ary = []

class Test
  def self.run &block
    define_method :run_method do
      # https://www.ruby-forum.com/topic/4416134#1117671
      eval %(ary << 1; puts 'complete'), block.binding
    end

    Test.new.run_method
  end
end

Test.run do
  ary << 1
  puts 'complete'
end

success.rb

ary = []

class Test
  def self.run &block
    define_method :run_method do
      # ary is in scope
      self.instance_eval &block
    end

    Test.new.run_method
  end
end

Test.run do
  ary << 1
  puts 'complete'
end