使用 shoulda 重构 Rails 模型上的 rspec 测试

了解后应该匹配器 https://github.com/thoughtbot/shoulda-matchers通过回答关于属性可访问性测试的另一个 StackOverflow 问题 https://stackoverflow.com/a/11849608/567863（并且认为它们非常棒），我决定尝试重构我在中所做的模型测试Rails 教程 http://ruby.railstutorial.org/试图使它们更加简洁和彻底。我这样做得益于模块文档的一些灵感Shoulda::Matchers::ActiveRecord http://rubydoc.info/github/thoughtbot/shoulda-matchers/master/frames and Shoulda::Matchers::ActiveModel http://rubydoc.info/github/thoughtbot/shoulda-matchers/master/frames， 也这个 StackOverflow 答案 https://stackoverflow.com/a/4611017/567863关于在模型中构建shoulda测试。然而，仍然有一些事情我不确定，我想知道如何才能使这些测试变得更好。

我将使用 Rails 教程中的用户规范作为示例，因为它是最详细的，并且涵盖了许多可以改进的领域。下面的代码示例在原来的基础上进行了更改用户规范.rb https://github.com/railstutorial/sample_app_2nd_ed/blob/master/spec/models/user_spec.rb，并向下替换代码，直到describe "micropost associations"线。该规范测试针对user.rb https://github.com/railstutorial/sample_app_2nd_ed/blob/master/app/models/user.rb模型，其工厂定义在工厂.rb https://github.com/railstutorial/sample_app_2nd_ed/blob/master/spec/factories.rb.

规格/模型/user_spec.rb

# == Schema Information
#
# Table name: users
#
#  id              :integer          not null, primary key
#  name            :string(255)
#  email           :string(255)
#  created_at      :datetime         not null
#  updated_at      :datetime         not null
#  password_digest :string(255)
#  remember_token  :string(255)
#  admin           :boolean          default(FALSE)
#
# Indexes
#
#  index_users_on_email           (email) UNIQUE
#  index_users_on_remember_token  (remember_token)
#

require 'spec_helper'

describe User do

  let(:user) { FactoryGirl.create(:user) }

  subject { user }

  describe "database schema" do
    it { should have_db_column(:id).of_type(:integer)
                              .with_options(null: false) }
    it { should have_db_column(:name).of_type(:string) }
    it { should have_db_column(:email).of_type(:string) }
    it { should have_db_column(:created_at).of_type(:datetime)
                              .with_options(null: false) }
    it { should have_db_column(:updated_at).of_type(:datetime)
                              .with_options(null: false) }
    it { should have_db_column(:password_digest).of_type(:string) }
    it { should have_db_column(:remember_token).of_type(:string) }
    it { should have_db_column(:admin).of_type(:boolean)
                              .with_options(default: false) }
    it { should have_db_index(:email).unique(true) }
    it { should have_db_index(:remember_token) }
  end

  describe "associations" do
    it { should have_many(:microposts).dependent(:destroy) }
    it { should have_many(:relationships).dependent(:destroy) }
    it { should have_many(:followed_users).through(:relationships) }
    it { should have_many(:reverse_relationships).class_name("Relationship")
                         .dependent(:destroy) }
    it { should have_many(:followers).through(:reverse_relationships) }
  end

  describe "model attributes" do
    it { should respond_to(:name) }
    it { should respond_to(:email) }
    it { should respond_to(:password_digest) }
    it { should respond_to(:remember_token) }
    it { should respond_to(:admin) }
    it { should respond_to(:microposts) }
    it { should respond_to(:relationships) }
    it { should respond_to(:followed_users) }
    it { should respond_to(:reverse_relationships) }
    it { should respond_to(:followers) }
  end

  describe "virtual attributes and methods from has_secure_password" do
    it { should respond_to(:password) }
    it { should respond_to(:password_confirmation) }
    it { should respond_to(:authenticate) }
  end

  describe "accessible attributes" do
    it { should_not allow_mass_assignment_of(:password_digest) }
    it { should_not allow_mass_assignment_of(:remember_token) }
    it { should_not allow_mass_assignment_of(:admin) }
  end

  describe "instance methods" do
    it { should respond_to(:feed) }
    it { should respond_to(:following?) }
    it { should respond_to(:follow!) }
    it { should respond_to(:unfollow!) }
  end

  describe "initial state" do
    it { should be_valid }
    it { should_not be_admin }
    its(:remember_token) { should_not be_blank }
    its(:email) { should_not =~ /\p{Upper}/ }
  end

  describe "validations" do
    context "for name" do
      it { should validate_presence_of(:name) }
      it { should_not allow_value(" ").for(:name) }
      it { should ensure_length_of(:name).is_at_most(50) }
    end

    context "for email" do
      it { should validate_presence_of(:email) }
      it { should_not allow_value(" ").for(:email) }
      it { should validate_uniqueness_of(:email).case_insensitive }

      context "when email format is invalid" do
        addresses = %w[user@foo,com user_at_foo.org example.user@foo.]
        addresses.each do |invalid_address|
          it { should_not allow_value(invalid_address).for(:email) }
        end
      end

      context "when email format is valid" do
        addresses = %w[[email protected] /cdn-cgi/l/email-protection [email protected] /cdn-cgi/l/email-protection [email protected] /cdn-cgi/l/email-protection [email protected] /cdn-cgi/l/email-protection]
        addresses.each do |valid_address|
          it { should allow_value(valid_address).for(:email) }
        end
      end
    end

    context "for password" do
      it { should ensure_length_of(:password).is_at_least(6) }
      it { should_not allow_value(" ").for(:password) }

      context "when password doesn't match confirmation" do
        it { should_not allow_value("mismatch").for(:password) }
      end
    end

    context "for password_confirmation" do
      it { should validate_presence_of(:password_confirmation) }
    end
  end

  # ...
end

关于这些测试的一些具体问题：

1. 是否值得测试数据库模式？中的一条评论上面提到的 StackOverflow 答案 https://stackoverflow.com/a/4611017/567863说“我只测试与行为相关的东西，我不考虑列或索引行为的存在。数据库列不会消失，除非有人故意删除它们，但你可以通过代码审查和信任”，我同意这一点，但是是否有任何有效的理由来测试数据库模式的结构，从而证明存在的合理性Shoulda::Matchers::ActiveRecord模块？也许只有重要的指标才值得测试……？
2. Do the should have_many测试下"associations"替换它们对应的should respond_to测试下"model attributes"？我无法判断是否should have_many测试只是寻找相关的has_many模型文件中的声明或实际上执行与以下相同的功能should respond_to.
3. 您还有其他意见/建议可以使这些测试在内容和结构上更加简洁/可读/彻底吗？

1) Shoulda::Matchers::ActiveRecord 模块不仅仅包含列和索引匹配器。我会在周围挖掘包含的课程 https://github.com/thoughtbot/shoulda-matchers/tree/master/lib/shoulda/matchers/active_record一点点，看看你能找到什么。这就是have_many, belong_to等来自。但郑重声明，我认为其中大部分内容没有什么价值。

2）是的，宏例如have_many测试的内容不仅仅是模型是否响应方法。来自源代码 https://github.com/thoughtbot/shoulda-matchers/blob/master/lib/shoulda/matchers/active_record/association_matcher.rb#L108-120，您可以准确地看到它正在测试什么：

def matches?(subject)
  @subject = subject
  association_exists? &&
    macro_correct? &&
    foreign_key_exists? &&
    through_association_valid? &&
    dependent_correct? &&
    class_name_correct? &&
    order_correct? &&
    conditions_correct? &&
    join_table_exists? &&
    validate_correct?
end

3）使测试更具可读性和/或更简洁绝对是一个需要回答的主观问题。每个人都会根据他们的背景和经验给你不同的答案。我个人会摆脱所有respond_to测试并用有价值的测试替换它们。当有人查看您的测试时，他们应该能够理解该类的公共 API。当我看到你的对象对“以下？”之类的内容做出响应时，我可以做出假设，但并不真正知道它的含义。这需要争论吗？它返回一个布尔值吗？是物体跟随某物，还是某物跟随物体？