hashy thing.rb

HashyThing = Struct.new(:name, :age) do
  def initialize(attributes={})
    super
    attributes.each { |key, val| send("#{key}=", val) }
    yield self if block_given?
  end

  def to_hash
    members.inject({}) do |res, key|
      res[key] = send(key)
      res
    end
  end
end

require 'test/unit'

class HashyThingTest < Test::Unit::TestCase
  def test_takes_a_hash
    thing = HashyThing.new(:name => 'Pat', :age => 23)
    assert_equal 23, thing.age
    assert_equal 'Pat', thing.name
  end

  def test_takes_a_block
    thing = HashyThing.new do |obj|
      obj.name = 'Pat'
      obj.age  = 23
    end
    assert_equal 23, thing.age
    assert_equal 'Pat', thing.name
  end

  def test_to_hash
    attrs = { :name => 'Pat', :age => 23 }
    thing = HashyThing.new(attrs)
    attrs.each do |key, val|
      assert_equal val, thing.to_hash[key.to_s]
    end
  end
end