todo_list.rb

class Item
  attr_accessor :description, :completed
  
  def initialize desc
    @description = desc
    @completed = false
  end
  
end

class TodoList
  def initialize
    @list = [Item.new("Write this program.")]
  end
  
  def show_list
    @list.reject do |item|
      item.completed
    end
  end
  
  def add_task desc=nil
    if desc.nil?
      "Must enter description"
    else
      @list.push Item.new desc
    end
  end
  
  def mark_complete item
    @list[item].completed = true
  end

end

@list = TodoList.new

def print_list
  @list.show_list.each_with_index do |item, index|
    puts "#{index}. #{item.description}"
  end
end

print_list

puts "Press 'a' + ENTER to add a ToDo"
puts "Press <Num> + ENTER to mark a Todo done"
puts "Press 'q' + ENTER to quit"

running = true

while running
  input = gets
  
  begin
    input = Integer input
  rescue
    input = input.chomp!
  end
    
  case input
    when "a"
      puts "Enter description"
      desc = gets
      @list.add_task desc
      print_list    
    when "q"
      running = false
    when 0..9999
      @list.mark_complete input
      print_list
  end
end

todo_list_spec.rb

require './todo_list'

describe 'list of todos' do
  before (:each) do
    @list = TodoList.new
  end
  
  it "returns the list" do
    @list.show_list[0].should be_an_instance_of Item
  end
  
  it "add a task" do
    @list.show_list.length.should == 1
    @list.add_task("figure this out")
    @list.show_list.length.should == 2
    
  end
  
  it "task will not be created without a description" do
    @list.add_task().should == "Must enter description"
  end
  
  it "checks off the task" do
    item = @list.show_list[0]
    @list.mark_complete(0)
    
    item.completed.should == true
  end
  
  it "does not return checked off task" do
    @list.add_task("New task")
    @list.mark_complete(1)
    
    @list.show_list.length.should == 1
  end
end