foo.rb

# Replace Inheritance with Delegation
# http://refactoring.com/catalog/replaceInheritanceWithDelegation.html

# class Roster < Array
#   attr_accessor :title

#   def to_s
#     out = "#{title}\n"
#     each do |item|
#       out += "#{item}\n"
#     end
#     return out
#   end
# end

# class Roster
#   attr_accessor :title

#   def initialize
#     @people = Array.new
#   end

#   def <<(person)
#     @people << person
#   end

#   def [](index)
#     @people[index]
#   end

#   def size
#     @people.size
#   end

#   def each
#     @people.each {|p| yield(p)}
#   end

#   def to_s
#     out = "#{title}\n"
#     each do |item|
#       out += "#{item}\n"
#     end
#     return out
#   end
# end

require 'forwardable'

class Roster
  extend Forwardable

  attr_accessor :title

  def initialize
    @people = Array.new
  end

  def_delegators :@people, :<<, :[], :size, :each

  def to_s
    out = "#{title}\n"
    each do |item|
      out += "#{item}\n"
    end
    return out
  end
end

require 'test/unit'

class RosterTest < Test::Unit::TestCase
  def setup
    @roster = Roster.new
    @roster.title = "Employees"
    @roster << "Joe"
  end
  
  def test_size
    assert_equal(1, @roster.size)
  end

  def test_index
    assert_equal("Joe", @roster[0])
  end

  def test_to_s
    assert_equal("Employees\nJoe\n", @roster.to_s)
  end
end