Rails中model测试的一些方法

2014-09-01 #rails #test #rspec #model

测试的哲学

测试应该是可靠的
测试应该容易书写
测试应该容易理解

一些妥协

速度不是测试中关注的重点
过于DRY的代码不是测试中关注的重点参考原文

Model的Specs

为当前的Model创建一个spec
可以使用factories来简化测试数据的维护和创建
为Model的validation，class，以及instance method写能够通过的测试用例

get started

A model spec should include tests for the following

factory默认生成的对象必须合法

describe Contact 
  it "has a valid factory" 
  it "is invalid without a firstname" 
  it "is invalid without a lastname" 
  it "returns a contact's full name as a string"

每一个测试用例只测试一件事情
每一个测试用例都必须明确
每一个用例的描述都以动词开头而不是should

####可以使用Factorygirl创建数据，然后使用Faker gem 可以用来创建随即的数据

require 'faker' 
FactoryGirl.define do 
  factory :contact do |f| 
    f.firstname { Faker::Name.first_name } 
    f.lastname { Faker::Name.last_name } 
  end 
end

不能通过validation的数据，应该是不合法的

可以使用Factory.build()实例化一个新的model，但是并不保存它

# spec/models/phone_spec.rb 
it "does not allow duplicate phone numbers per contact" do 
  contact = Factory(:contact) 
  Factory(:phone, contact: contact, phone_type: "home", number: "785-555-1234") 
  Factory.build(:phone, contact: contact, phone_type: "mobile", number: "785-555-1234").should_not be_valid 
end

Validation的部分

# app/models/phone.rb 
validates :phone, uniqueness: { scope: :contact_id }

测试validation的时候要记住，不光是测试所有数据都合法的happy path，同样还需要测试错误的条件。

类和成员方法要能够按预期运行

def name 
  [firstname, lastname].join " "  
end

为这个特性编写测试用例

it "returns a contact's full name as a string" do 
  contact = Factory(:contact, firstname: "John", lastname: "Doe")
  contact.name.should == "John Doe" 
end

测试类方法

特册应该返回name以给定字母开头的contact的list

# app/models/contact.rb 
def self.by_letter(letter) 
  where("lastname LIKE ?", "#{letter}%").order(:lastname) 
end

然后测试它

# spec/models/contact_spec.rb 
require 'spec_helper' 
describe Contact do 
  # validation examples ... 
  it "returns a sorted array of results that match" do
    smith = Factory(:contact, lastname: "Smith") 
    jones = Factory(:contact, lastname: "Jones") 
    johnson = Factory(:contact, lastname: "Johnson") 
    Contact.by_letter("J").should == [johnson, jones] 
  end 
end

参考资料： How I learned to test my Rails applications, Part 3: Model specs