Ruby on rails Rails:Shoulda在更新时匹配并验证用户名

模型验证：

validates :username, uniqueness: true, format: { with: /\A[a-zA-Z0-9_.-@]+\Z/i, message: "must contain only letters, numbers or _*-@" }, on: :update, :if => :username_changed?

Rspec：

require 'spec_helper'

describe User, "references" do
  it { should have_and_belong_to_many(:roles) }
  it { should belong_to(:account_type) }
  it { should belong_to(:primary_sport).class_name("Sport") }
  it { should belong_to(:school) }
  it { should belong_to(:city) }
  it { should validate_presence_of(:email) }
  it { should validate_uniqueness_of(:email) }
  it { should allow_value("test@test.com").for(:email) }
  it { should_not allow_value("test.com").for(:email) }

  describe "validation of username", focus: true do
    before(:each) do
      @user = User.new(email: Faker::Internet.email, password: "password", password_confirmation: "password", username: "test123", agreed_to_age_requirements: true)
    end

    it "should be valid" do
      @user.save
      @user.should be_valid
    end

    it "should not be valid with incorrect characters in username" do
      @user.username = "test@@@!!!"
      @user.should_not be_valid
    end
  end
end

工厂女工：

FactoryGirl.define do
  factory :user do
    email Faker::Internet.email
    password "password"
    password_confirmation "password"
    agreed_to_age_requirements true
    username Faker::Internet.user_name
  end 
end

---

基本上，我只是想测试自定义验证用户名的唯一性和指定格式的唯一性

您的问题是什么？使用Rspec，我将如何编写一个测试来测试：

validates:username，university:true，format:{with://\a[a-zA-Z0-9.-@]+\Z/I，消息：“必须只包含字母、数字或*-@”，on:：update，：if=>：username\u changed？

@Vimsha-我用最近一次编写测试的尝试更新了我的问题