Rspec 代码规范和最佳实践

Posted on September 22, 2013

测试环境

Gemfile

group :development do
  gem "rspec-rails"
  gem 'factory_girl_rails'
end

group :test do
  gem "rspec-rails"
  gem 'factory_girl_rails'
  gem 'shoulda-matchers'
  gem 'webmock'
  gem 'database_cleaner'
  gem 'capybara'
end

rspec-rails 会添加如下gem:

rspec
rspec-core
rspec-expectations # 提供 should, should_not 和许多内建matcher
rspec-mocks
rspec-rails

factory_girl_rails 会添加如下gem:

  factory_girl
  factory_girl_rails

测试规范

Model 测试

测试文件所在目录spec/models/

测试覆盖

  • 所有的 ActiveRecord model 需要一个对应的模型测试文件

  • validations

  • associations

  • constants

  • class method

  • instance method

测试规范

  1. 实例方法测试, 传入标识应该是“#实例方法名称” 如 it "#published?"

  2. 类方法测试, 传入标识应该是“.类方法名称” 如 it ".list_deals"

代码示例

    describe Job do
      describe "validations" do
        it { should validate_numericality_of(:amount).only_integer }
        it { should validate_presence_of(:city_id) }
      end

      describe "associations" do
        it { should belong_to(:category) }
      end

      describe "mass assignments" do
        it { should_not allow_mass_assignment_of(:password) }
      end

      describe "constants" do
        it { Job::Cities.should be_frozen }
        it { SomeConstant.should eq(123)  }
        end
      end

      describe "class method" do
        it ".some_class_method" do
          ......
        end
        ....
      end

      describe "instance method" do
        it "#published?" do
          FactoryGirl.create(:published_job).should be_published
        end

        ....
      end

    end

Controller 测试

测试文件所在目录spec/controllers/

测试覆盖

  • 所有前后台的controllers,都需要一个对应的控制器测试文件

  • 每一个action需要一个describe块

  • 在action的每一个出口,至少需要一个it覆盖

  • respond_with 测试返回状态码

  • render_template 测试render的template

  • assigns(...) 测试实例变量

测试规范

  1. 每个action的测试块,传入标识应该是“http动词 action名称”,列如describe "POST create"

代码示例

    ...
    describe "POST create" do
      describe "with valid params" do
        it "creates a new Student" do
          expect {
            post :create, {:student => valid_attributes}, valid_session
          }.to change(Student, :count).by(1)
        end

        it "assigns a newly created student as @student" do
          post :create, {:student => valid_attributes}, valid_session
          assigns(:student).should be_a(Student)
          assigns(:student).should be_persisted
        end

        it "redirects to the created student" do
          post :create, {:student => valid_attributes}, valid_session
          response.should redirect_to(Student.last)
        end
      end

      describe "with invalid params" do
        it "assigns a newly created but unsaved student as @student" do
          # Trigger the behavior that occurs when invalid params are submitted
          Student.any_instance.stub(:save).and_return(false)
          post :create, {:student => { "name" => "invalid value" }}, valid_session
          assigns(:student).should be_a_new(Student)
        end

        it "re-renders the 'new' template" do
          # Trigger the behavior that occurs when invalid params are submitted
          Student.any_instance.stub(:save).and_return(false)
          post :create, {:student => { "name" => "invalid value" }}, valid_session
          response.should render_template("new")
        end
      end
    end

Requests 测试

测试文件所在目录spec/requests/

测试覆盖

  • 前台页面如果有跳转的,需要对应的请求测试文件

  • response.status 测试返回状态码

  • response.should redirect_to 测试跳转

测试规范

  1. 每个action的测试块,传入标识应该是“http动词 action名称”,列如describe "Get index"

Routing 测试

测试文件所在目录spec/routing/

测试覆盖

  • 所有前后台的controllers,都需要一个对应的路由测试文件

  • 使用it覆盖每一个路由

测试规范

  1. 每个路由测试块,传入标识应该是“routes to #action名称”,列如it "routes to #edit"

代码示例

    describe StudentsController do
      describe "routing" do

        it "routes to #index" do
          get("/students").should route_to("students#index")
        end

        it "routes to #new" do
          get("/students/new").should route_to("students#new")
        end

        it "routes to #show" do
          get("/students/1").should route_to("students#show", :id => "1")
        end

        it "routes to #edit" do
          get("/students/1/edit").should route_to("students#edit", :id => "1")
        end

        it "routes to #create" do
          post("/students").should route_to("students#create")
        end

        it "routes to #update" do
          put("/students/1").should route_to("students#update", :id => "1")
        end

        it "routes to #destroy" do
          delete("/students/1").should route_to("students#destroy", :id => "1")
        end

      end
    end

集成测试

测试文件所在目录spec/features/

测试覆盖

  • 所有前台的controllers,都需要一个对应的集成测试文件

  • 使用it覆盖所有的get请求

  • 使用page.should have_title测试title

  • 使用page.should have_content(...) 测试关键内容

  • 使用click_link('...')测试关键链接

测试规范

  1. 每个路由测试块,传入标识应该是“routes to #action名称”,列如it "routes to #edit"

代码示例

    describe "front_controller" do
      it "#index" do
        visit '/'
        page.should have_title('招聘首页')
        page.should have_content('职位搜索')
      end

      it "#brand" do
        visit '/brand'
        page.should have_title('招聘入口')
        click_link('点击进入')
        expect(page).to have_title('招聘首页')
      end

    end

Helper 测试

测试文件所在目录spec/helpers/

测试覆盖

  • 所有前台的controllers,都需要一个对应的helper测试文件

  • 测试关键helper即可


最佳实践

目的: 使rspec测试结构清晰,容易维护,可读性强。

  1. 正确的描述(describe)

    • 最外层的descibe应该和所测试的model,controller,helper等对应的class/module名称一致

    • 测试类方法应该是descibe "#class_method"

    • 测试实例方法应该是descibe ".class_method"

    • 分情况测试时使用context:context "当...情况下..."

  2. 在有明确测试对象时,尽量使用expect,代替should should_not 如:

     expect(some object or block).to some_matcher     #代替 should
     expect(some object or block).to_not some_matcher #代替 should_not
    

    详细内容请点击should and should_not syntax

  3. 每个it里只有一个断言,这样每个断言对应一个描述,增强可读性:

     it 'creates a new user' do
       User.count.should == @count + 1
     end
    
     it 'sets a flash message' do
       flash[:notice].should be
     end
    
  4. 使用谓词构造动态的matcher,已到达更好的易读性(更贴近自然语言):

     expect(actual).to be_xxx         # passes if actual.xxx?
     expect(actual).to have_xxx(:arg) # passes if actual.has_xxx?(:arg)
    

    猛烈点击Predicate matchers

  5. 使用subject来指定多个测试中的固定测试对象,避免反复引用:

     subject { @user.address }
     it { should be_valid }
     it { should be... }
    
  6. 正确区别使用describecontext

    context是describe都定义了一个example group, 其中可以定义若干example(使用it/specify),也可以嵌套其他的example group

    context是describe的别名,也就是他们没有功能上的区别,区别是语义上的:

    describe是对测试功能模块的划分

    context是对同一个功能模块对不同情况下的划分

    猛烈点击获得更详细的论述describe vs. context in rspec

    另外测试加上nested参数可以使输出嵌套:如 bundle exec rspec spec/models/job_spec.rb -cf nested

  7. 注重边界测试和无效值测试:

     describe "#month_in_english(month_id)" do
       context "when valid" do
         it "should return 'January' for 1" # lower boundary
         it "should return 'March' for 3"
         it "should return 'December' for 12" # upper boundary
       context "when invalid" do
         it "should return nil for 0"
         it "should return nil for 13"
       end
     end
    
  8. 慎用before :all 因为before :all 里的操作不在事务里,所有需要在after :all中手动清除在before :all里创建的数据

  9. 容易引起误解的before {...},该结构没有传递alleach,其实它实现的是each,常用作外围的before each(也是在事务里),但是经常被误认为是before all

    嵌套before和after的执行顺序:

     outer before all
     inner before all
     outer before each
     inner before each
     testing....
     inner after each
     outer after each
     inner after all
     outer after all
    

    这里有个测试的例子Rspec Gotchas: before, after, all, and each

  10. 不要过度mock

##其他技巧/笔记

  1. 使用its进行属性测试,传递symbol或者字符串代表属性,可以表示嵌套属性测试 Attribute of subject

  2. 如果最顶层是一个class,测试对象将(隐式)为该class的一个实例,可以用方法subject获取,同样可以用subject方法(显示)指定当前测试对象Subject

    该顶层class可以通过方法 described_class()活动Described class

  3. specify it example 是别名关系,区别仅仅是语义上的:

     describe Array do
       describe "with 3 items" do
         before { @arr = [1, 2, 3] }
         specify { @arr.should_not be_empty } #明确指定了测试对象
       end
    
       describe "with 3 items" do
         subject { [1, 2, 3] }
         it { should_not be_empty }  #使用隐式的测试对象
       end
     end
    
  4. Let 和 let!

    这2个helper都用于实现memoized: 第一次调用的结果会被缓存起来,之后的调用将会使用该结果。

    二者的区别:

    let 是延迟执行(lazy-evaluated),当第一次显示调用是才会执行

    let! 在每个用例的before each中自动调用

    Let and let!

  5. 共享用例组(Shared example group)用于提取多个group之间要测试的通用的行为. Shared example group

  6. rspec提供了大量内建matchers:Built in matchers

  7. mock 常量:stub_const("SomeNameSpace::Myconstant", 123)

  8. rspec 中使用jbuilder,默认不会render view,需要手动render_views Why is JBuilder not returning a response body


###参考资料:

https://www.relishapp.com/rspec/

http://www.wulftone.com/2012/01/22/rspec-gotchas-before-after-all-and-each/

http://kpumuk.info/ruby-on-rails/my-top-7-rspec-best-practices/

http://eggsonbread.com/2010/03/28/my-rspec-best-practices-and-tips/

http://blog.carbonfive.com/2010/10/21/rspec-best-practices/