Test validations in ActiveRecord

user_spec.rb

require 'spec_helper'

module ActiveModel
  class Errors
    def error_names
      @_error_names ||= { }
    end
    
    def add_with_save_names(attribute, message = nil, options = {})
      message ||= :invalid
      if message.is_a?(Proc)
        message = message.call
      end
      error_names[attribute] ||= []
      error_names[attribute] << message
      add_without_save_names(attribute, message, options)
    end

    alias_method_chain :add, :save_names
  end
end

describe User do
  it "should not allow to short name" do
    u = User.new(:name => "a")
    u.valid?
    puts u.errors.error_names
    u.errors.error_names[:name].should include(:too_short)
  end
end