验证可能依赖于方法的 Rails 模型属性时出错

Question

我在 Rails 方面的测试经验不多，所以我不完全了解测试框架的工作原理。

我得到的错误：

Failure/Error: self.slug ||= name.parameterize
NoMethodError: 
undefined method `parameterize' for nil:NilClass

即使我使用 FactroyGirl（或使用 Organization.new(...).save 的老式方法）创建一个包含所有属性的新组织，也会出现此错误。

我明白为什么会出现错误，我不明白 name 是如何被评估为 nil 的，因此我不明白如何以正确的方式编写测试。

我已使用 puts "short_name: #{org.short_name}".

等语句验证组织及其属性存在于测试范围内

require 'rails_helper'

class Organization < ActiveRecord::Base

[....]

validates :name, :slug, uniqueness: { case_sensitive: false }
  validates :name, :short_name, :slug, presence: true
  validates :name, length: { maximum: 255 }
  validates :short_name, length: { maximum: 20 }
  validates :slug, length: { maximum: 200 }

before_validation :generate_slug
  def generate_slug
    self.slug ||= name.parameterize
  end

  before_validation :generate_short_name
  def generate_short_name
    self.short_name ||= begin
      if name?
        if name.size > 20
          name.split(/[ -]/).first.first(20)
        else
          name
        end
      end
    end
  end
end

架构：

create_table "organizations", force: :cascade do |t|
    t.integer  "organization_type_id",   limit: 4
    t.string   "name",                   limit: 255
    t.string   "short_name",             limit: 20
    t.string   "slug",                   limit: 200
    t.text     "description",            limit: 65535
    t.integer  "year_founded",           limit: 2, unsigned: true
    t.datetime "last_published_date"
    t.date     "notification_sent_date"
    t.datetime "last_imported_at"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
  end

组织工厂：

FactoryGirl.define do
  factory :organization, class: Organization do
    name 'Example & Co'

    trait :all_fields do
      slug 'example-co'
      short_name 'Example & Co'
      description ‘This is a description.’
      year_founded 2010
    end
  end
end

以下所有验证测试都适用于其他组织属性。如果用户未提供 slug，generate_slug 方法应该从 name 属性创建一个 url 安全 slug。注意：我不是代码的作者，我只是为承包商构建的应用构建测试套件。

测试：

第一个测试通过了，我把它包含在 information/verification

RSpec.describe Organization, :type => :model do

  #validating my factory:      
  describe 'FactoryGirl' do
    it 'factory generating all fields should be valid' do
      create(:organization, :all_fields).should be_valid
      build(:organization, :all_fields).should_not be_valid
    end

    it 'factory generating name field should be valid' do
      create(:organization).should be_valid
      build(:organization).should_not be_valid
    end
  end

出错的测试：

describe 'name' do
  let(:org) {FactoryGirl.build(:organization, :all_fields)} 
  context 'is valid' do
    # this is the only test on #name that fails
    it { should validate_presence_of(:name) }
  end
end

describe 'slug' do
  let(:org) {FactoryGirl.build(:organization, :all_fields)}
  context 'is valid' do
    # this is the only test on #slug that fails,     
    it { should validate_presence_of(:slug) }
  end
end

describe 'short_name' do
  # All of the tests on short_name fail
  let(:org) {FactoryGirl.build(:organization, :all_fields)}
  context 'is valid' do
    it { should validate_presence_of(:short_name) }
    it { should have_valid(:short_name).when(org.short_name, 'Example & Co') } 
    it { should validate_length_of(:short_name).is_at_most(20) }      
  end

  context 'is not valid' do
    it { should_not have_valid(:short_name).when('a' * 21) }       
  end
end

Answer 1

第一个：

您需要在测试中设置正确的主题。这是所有 it 行将引用的对象。您确实创建了一个 let，但由于您从未明确将其设置为主题，因此测试选择了隐式主题（在您的情况下默认为 Organization.new）

要设置明确的主题，您可以这样写：

describe 'name' do
  subject { FactoryGirl.build(:organization, :all_fields) } 

  it { should validate_presence_of(:name) }
  # or with the new syntax
  it { is_expected.to validate_presence_of(:name) }
end

您可以在此处阅读有关隐式与显式主题和单行的更多信息：http://www.relishapp.com/rspec/rspec-core/v/3-4/docs/subject/one-liner-syntax

第二个：

另一个问题是，假设您正在使用 shoulda-matchers gem，它会将 name 设置为 nil 以便在属性时看到不存在，则应发生验证错误。

但是当名称设置为 nil 时，before_validation 回调会抛出一个错误，因为它假设总是找到 name.

您可以像这样修改回调 (example in rails documentation):

before_validation :generate_slug
def generate_slug
  self.slug ||= name.parameterize if attribute_present?("name")
end

第三名：

一个建议。如果你设置了工厂并且你有 shoulda-matchers gem，你可以写出非常简洁的规范。比如像这样。

RSpec.describe Organization, :type => :model do
  # If you fix the callback you don't even need 
  # to set explicit subject here

  it { is_expected.to validate_presence_of(:name) }
  it { is_expected.to validate_lenght_of(:name).is_at_most(255) }
  ... etc

  # Add custom contexts only for the before_validation callbacks,
  # because shoulda-matchers cannot test them.
  # One possible way (there are different ways and opinions on how
  # should implement this kind of test):
  describe '#slug' do
    let(:organization) { described_class.new(name: 'Ab cd', slug: slug) }

    before { organization.valid? }

    subject { organization.slug }

    context 'when it is missing' do
      let(:slug) { nil }
      let(:result) { 'ab_cd' }

      it 'gets created' do
        expect(subject).to eq(result)
      end
    end

    context 'when it is not missing' do
      let(:slug) { 'whatever' }

      it "won't change" do
        expect(subject).to eq(slug)
      end
    end
  end
end

有关更多示例，您可以浏览 the shoulda-matchers documentation。

验证可能依赖于方法的 Rails 模型属性时出错

Error validating Rails model attributes that can depend on a method

ruby

rspec

ruby-on-rails

shoulda

factory-bot