ruby-on-rails-3 – RSpec和Rails 3 – 简单测试失败

我正在做一些简单的测试,以确保用户在注册时有效.失败的测试是“应该要求用户名”.产生的错误是：

Failure/Error: new_user(:username => '').should have(1).error_on(:username)
       expected 1 error on :username,got 0

user_spec.rb

require File.dirname(__FILE__) + '/../spec_helper'

describe User do
  def new_user(attributes = {})
    attributes[:username] ||= 'foo'
    attributes[:email] ||= 'foo@example.com'
    attributes[:password] ||= 'abc123'
    attributes[:password_confirmation] ||= attributes[:password]
    User.new(attributes)
  end

  before(:each) do
    User.delete_all
  end

  it "should be valid" do
    new_user.should be_valid
  end

  it "should require username" do
    new_user(:username => '').should have(1).error_on(:username)
  end
end

User.rb

class User < ActiveRecord::Base
  # new columns need to be added here to be writable through mass assignment
  attr_accessible :username,:email,:password,:password_confirmation

  attr_accessor :password
  before_save :prepare_password

  validates_presence_of :username
  validates_uniqueness_of :username,:allow_blank => true
  validates_format_of :username,:with => /^[-w._@]+$/i,:allow_blank => true,:message => "should only contain letters,numbers,or .-_@"
  validates_format_of :email,:with => /^[-a-z0-9_+.]+@([-a-z0-9]+.)+[a-z0-9]{2,4}$/i
  validates_presence_of :password,:on => :create
  validates_confirmation_of :password
  validates_length_of :password,:minimum => 4,:allow_blank => true

  # login can be either username or email address
  def self.authenticate(login,pass)
    user = find_by_username(login) || find_by_email(login)
    return user if user && user.password_hash == user.encrypt_password(pass)
  end

  def encrypt_password(pass)
    BCrypt::Engine.hash_secret(pass,password_salt)
  end

  private

  def prepare_password
    unless password.blank?
      self.password_salt = BCrypt::Engine.generate_salt
      self.password_hash = encrypt_password(password)
    end
  end
end

正如您所看到的,我只是创建一个新用户(暂时不使用工厂,只是简单的测试),用户名为空,而且由于validates_presence_of：username,它应该有错误.

我错过了什么？