gistfile1.rb

## task_spec.rb
require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')

describe Task do
  include ValidTaskAttributes 
    # o módulo ValidTaskAttributes define o método valid_task que retorna 
    #{
    #  :name => "Task name",
    #  :description => "Task description",
    #  :alias => "task_alias",
    #  :due_date => Date.today,
    #  :priority => 1,
    #  :percentage => 9.99,
    #} 

  describe 'validations' do
    subject { Task.create(valid_task) } 
    #aqui eu crio um objeto do tipo Task no banco. ele está sendo salvo com sucesso
    
    it { should validate_presence_of(:name) }
    it { should validate_presence_of(:alias) }

    it { should validate_uniqueness_of(:name) }
    it { should validate_uniqueness_of(:alias) }

    it { should validate_numericality_of(:priority, :only_integer => true, :greater_than_or_equal_to => 0, :less_than_or_equal_to => 10) }
    it { should validate_numericality_of(:percentage, :greater_than_or_equal_to => 0, :less_than_or_equal_to => 100, :allow_nil => true) }
  end
  
  describe 'associations' do
    subject { Task.create(valid_task) }
    
    it { should belong_to(:parent, :class_name => 'Task') }
    it { should have_many(:children, :class_name => 'Task', :foreign_key => 'parent_id') }
  end
end

## task.rb

class Task < ActiveRecord::Base
  belongs_to :parent, :class_name => 'Task'
  has_many :children, :class_name => 'Task', :foreign_key => 'parent_id'

  validates_presence_of :name
  validates_presence_of :alias  

  validates_uniqueness_of :name
  validates_uniqueness_of :alias
  
  validates_numericality_of :priority, :only_integer => true, :greater_than_or_equal_to => 0, :less_than_or_equal_to => 10
  validates_numericality_of :percentage, :greater_than_or_equal_to => 0, :less_than_or_equal_to => 100, :allow_nil => true
end