如何在测试中使用上下文？

Question

please help write tests with context.

model Album:

class Album < ActiveRecord::Base
  validates :title, presence: true, length: { maximum:  50, minimum: 3 }, uniqueness: { case_sensitive: false }
  validates :description, presence: true, length: { maximum:  600, minimum: 10 }
end

I wrote tests for model Album:

describe Album do
  it "has a valid factory" do
    expect(FactoryGirl.create(:album)).to be_valid
  end

  it "is invalid without title" do
    expect(FactoryGirl.build(:album, title: nil)).not_to be_valid
  end  

  it "is invalid with duplicate title" do
    FactoryGirl.create(:album, title: 'qwerty')
    expect(FactoryGirl.build(:album, title: 'qwerty')).not_to be_valid
  end 

  it "is valid with different title" do
    FactoryGirl.create(:album, title: 'zxcvbn')
    expect(FactoryGirl.build(:album, title: 'asdfgh')).to be_valid
  end        
end

these tests worked OK. but i need use context:

describe Album do
  it "has a valid factory" do
    expect(FactoryGirl.create(:album)).to be_valid
  end

  describe '#title' do
    context "invalid" do
      it "is invalid without title" do
        expect(FactoryGirl.build(:album, title: nil)).not_to be_valid
      end  

      it "is invalid with long title" do
        expect(FactoryGirl.build(:album, title: 'If you liked my series on practical advice for adding reliable tests to your Rails apps, check out the expanded ebook version. Lots of additional, exclusive content and a complete sample Rails application.')).not_to be_valid
      end        

      it "is invalid with duplicate title" do
        FactoryGirl.create(:album, title: 'qwerty')
        expect(FactoryGirl.build(:album, title: 'qwerty')).not_to be_valid
      end       
    end

    context "valid" do
      it "is valid with title" do
        expect(FactoryGirl.build(:album, title: 'good title')).not_to be_valid
      end  

      it "is valid with different title" do
        FactoryGirl.create(:album, title: 'zxcvbn')
        expect(FactoryGirl.build(:album, title: 'asdfgh')).to be_valid
      end  
    end
  end      
end

but these tests is not DRY. please help write the test with context again.

ps: good practices that I tried to use:

1. checking limiting cases (a very small value, very great value, average value)
2. use contexts for the organization code
3. each test should be in a separate method

Answer 1

Your tests using context looks okay. But, you can write better tests using context by following the best practices. See better specs guidelines to see how to write better RSpec tests.

Also, see the following classic example of using context from the The RSpec Style Guide

# A classic example for use of contexts in a controller spec is creation or update when the object saves successfully or not.

describe ArticlesController do
  let(:article) { mock_model(Article) }

  describe 'POST create' do
    before { Article.stub(:new).and_return(article) }

    it 'creates a new article with the given attributes' do
      Article.should_receive(:new).with(title: 'The New Article Title').and_return(article)
      post :create, article: { title: 'The New Article Title' }
    end

    it 'saves the article' do
      article.should_receive(:save)
      post :create
    end

    context 'when the article saves successfully' do
      before { article.stub(:save).and_return(true) }

      it 'sets a flash[:notice] message' do
        post :create
        flash[:notice].should eq('The article was saved successfully.')
      end

      it 'redirects to the Articles index' do
        post :create
        response.should redirect_to(action: 'index')
      end
    end

    context 'when the article fails to save' do
      before { article.stub(:save).and_return(false) }

      it 'assigns @article' do
        post :create
        assigns[:article].should be_eql(article)
      end

      it 're-renders the "new" template' do
        post :create
        response.should render_template('new')
      end
    end
  end
end