RSpec 风格指南

# bad
describe Article do

  describe '#summary' do

    context 'when there is a summary' do

      it 'returns the summary' do
        # ...
      end
    end
  end
end

# good
describe Article do
  describe '#summary' do
    context 'when there is a summary' do
      it 'returns the summary' do
        # ...
      end
    end
  end
end

# bad
describe Article do
  describe '#summary' do
    context 'when there is a summary' do
      # ...
    end
    context 'when there is no summary' do
      # ...
    end

  end
  describe '#comments' do
    # ...
  end
end

# good
describe Article do
  describe '#summary' do
    context 'when there is a summary' do
      # ...
    end

    context 'when there is no summary' do
      # ...
    end
  end

  describe '#comments' do
    # ...
  end
end

# bad
describe Article do
  subject { FactoryBot.create(:some_article) }
  describe '#summary' do
    # ...
  end
end

# good
describe Article do
  subject { FactoryBot.create(:some_article) }

  describe '#summary' do
    # ...
  end
end

# bad
describe Article do
  subject { FactoryBot.create(:some_article) }
  let(:user) { FactoryBot.create(:user) }
  before do
    # ...
  end
  after do
    # ...
  end
  describe '#summary' do
    # ...
  end
end

# good
describe Article do
  subject { FactoryBot.create(:some_article) }
  let(:user) { FactoryBot.create(:user) }

  before do
    # ...
  end

  after do
    # ...
  end

  describe '#summary' do
    # ...
  end
end

# bad
describe '#summary' do
  let(:item) { double('something') }

  it 'returns the summary' do
    # ...
  end
  it 'does something else' do
    # ...
  end
  it 'does another thing' do
    # ...
  end
end

# good
describe '#summary' do
  let(:item) { double('something') }

  it 'returns the summary' do
    # ...
  end

  it 'does something else' do
    # ...
  end

  it 'does another thing' do
    # ...
  end
end

# bad
describe Article do
  before do
    # ...
  end

  let(:user) { FactoryBot.create(:user) }
  subject { FactoryBot.create(:some_article) }

  describe '#summary' do
    # ...
  end
end

# good
describe Article do
  subject { FactoryBot.create(:some_article) }
  let(:user) { FactoryBot.create(:user) }

  before do
    # ...
  end

  describe '#summary' do
    # ...
  end
end

# bad
describe Article do
  before do
    # ...
  end

  after do
    # ...
  end

  let(:user) { FactoryBot.create(:user) }
  subject { FactoryBot.create(:some_article) }

  describe '#summary' do
    # ...
  end
end

# good
describe Article do
  subject { FactoryBot.create(:some_article) }
  let(:user) { FactoryBot.create(:user) }

  before do
    # ...
  end

  after do
    # ...
  end

  describe '#summary' do
    # ...
  end
end

# bad
it 'has 200 status code if logged in' do
  expect(response).to respond_with 200
end

it 'has 401 status code if not logged in' do
  expect(response).to respond_with 401
end

# good
context 'when logged in' do
  it { is_expected.to respond_with 200 }
end

context 'when logged out' do
  it { is_expected.to respond_with 401 }
end

# bad - needs refactoring
describe '#attributes' do
  context 'the returned hash' do
    it 'includes the display name' do
      # ...
    end

    it 'includes the creation time' do
      # ...
    end
  end
end

# bad - the negative case needs to be tested, but isn't
describe '#attributes' do
  context 'when display name is present' do
    before do
      article.display_name = 'something'
    end

    it 'includes the display name' do
      # ...
    end
  end
end

# good
describe '#attributes' do
  subject(:attributes) { article.attributes }
  let(:article) { FactoryBot.create(:article) }

  context 'when display name is present' do
    before do
      article.display_name = 'something'
    end

    it { is_expected.to include(display_name: article.display_name) }
  end

  context 'when display name is not present' do
    before do
      article.display_name = nil
    end

    it { is_expected.not_to include(:display_name) }
  end
end

# bad
it 'finds shortest path' do
  tree = Tree.new(1 => 2, 2 => 3, 2 => 6, 3 => 4, 4 => 5, 5 => 6)
  expect(dijkstra.shortest_path(tree, from: 1, to: 6)).to eq([1, 2, 6])
end

it 'finds longest path' do
  tree = Tree.new(1 => 2, 2 => 3, 2 => 6, 3 => 4, 4 => 5, 5 => 6)
  expect(dijkstra.longest_path(tree, from: 1, to: 6)).to eq([1, 2, 3, 4, 5, 6])
end

# good
let(:tree) { Tree.new(1 => 2, 2 => 3, 2 => 6, 3 => 4, 4 => 5, 5 => 6) }

it 'finds shortest path' do
  expect(dijkstra.shortest_path(tree, from: 1, to: 6)).to eq([1, 2, 6])
end

it 'finds longest path' do
  expect(dijkstra.longest_path(tree, from: 1, to: 6)).to eq([1, 2, 3, 4, 5, 6])
end

# bad
before { @name = 'John Wayne' }

it 'reverses a name' do
  expect(reverser.reverse(@name)).to eq('enyaW nhoJ')
end

# good
let(:name) { 'John Wayne' }

it 'reverses a name' do
  expect(reverser.reverse(name)).to eq('enyaW nhoJ')
end

# bad
describe 'GET /articles' do
  let(:article) { FactoryBot.create(:article, owner: owner) }

  before { page.driver.get '/articles' }

  context 'when user is the owner' do
    let(:user) { owner }

    it 'shows all owned articles' do
      expect(page.status_code).to be(200)
      contains_resource resource
    end
  end

  context 'when user is an admin' do
    let(:user) { FactoryBot.create(:user, :admin) }

    it 'shows all resources' do
      expect(page.status_code).to be(200)
      contains_resource resource
    end
  end
end

# good
describe 'GET /articles' do
  let(:article) { FactoryBot.create(:article, owner: owner) }

  before { page.driver.get '/articles' }

  shared_examples 'shows articles' do
    it 'shows all related articles' do
      expect(page.status_code).to be(200)
      contains_resource resource
    end
  end

  context 'when user is the owner' do
    let(:user) { owner }

    include_examples 'shows articles'
  end

  context 'when user is an admin' do
    let(:user) { FactoryBot.create(:user, :admin) }

    include_examples 'shows articles'
  end
end

# good
describe 'GET /devices' do
  let(:resource) { FactoryBot.create(:device, created_from: user) }

  it_behaves_like 'a listable resource'
  it_behaves_like 'a paginable resource'
  it_behaves_like 'a searchable resource'
  it_behaves_like 'a filterable list'
end

# bad
describe '#summary' do
  before(:example) do
    # ...
  end

  # ...
end

# good
describe '#summary' do
  before do
    # ...
  end

  # ...
end

# bad
describe '#summary' do
  before(:all) do
    # ...
  end

  # ...
end

# good
describe '#summary' do
  before(:context) do
    # ...
  end

  # ...
end

# good - one expectation per example
describe ArticlesController do
  #...

  describe 'GET new' do
    it 'assigns a new article' do
      get :new
      expect(assigns[:article]).to be_a(Article)
    end

    it 'renders the new article template' do
      get :new
      expect(response).to render_template :new
    end
  end
end

# good - multiple expectations with aggregated failures
describe ArticlesController do
  #...

  describe 'GET new', :aggregate_failures do
    it 'assigns new article and renders the new article template' do
      get :new
      expect(assigns[:article]).to be_a(Article)
      expect(response).to render_template :new
    end
  end

  # ...
end

# bad
it { expect(hero.equipment).to be_heavy }
it { expect(hero.equipment).to include 'sword' }

# good
subject(:equipment) { hero.equipment }

it { expect(equipment).to be_heavy }
it { expect(equipment).to include 'sword' }

# bad
describe Article do
  subject { FactoryBot.create(:article) }

  it 'is not published on creation' do
    expect(subject).not_to be_published
  end
end

# good
describe Article do
  subject { FactoryBot.create(:article) }

  it 'is not published on creation' do
    is_expected.not_to be_published
  end
end

# even better
describe Article do
  subject(:article) { FactoryBot.create(:article) }

  it 'is not published on creation' do
    expect(article).not_to be_published
  end
end

# bad
describe Article do
  context 'when there is an author' do
    subject(:article) { FactoryBot.create(:article, author: user) }

    it 'shows other articles by the same author' do
      expect(article.related_stories).to include(story1, story2)
    end
  end

  context 'when the author is anonymous' do
    subject(:article) { FactoryBot.create(:article, author: nil) }

    it 'matches stories by title' do
      expect(article.related_stories).to include(story3, story4)
    end
  end
end

# good
describe Article do
  context 'when article has an author' do
    subject(:article) { FactoryBot.create(:article, author: user) }

    it 'shows other articles by the same author' do
      expect(article.related_stories).to include(story1, story2)
    end
  end

  context 'when the author is anonymous' do
    subject(:guest_article) { FactoryBot.create(:article, author: nil) }

    it 'matches stories by title' do
      expect(guest_article.related_stories).to include(story3, story4)
    end
  end
end

# bad
describe 'Article' do
  subject(:article) { Article.new }

  it 'indicates that the author is unknown' do
    allow(article).to receive(:author).and_return(nil)
    expect(article.description).to include('by an unknown author')
  end
end

# good - with correct subject initialization
describe 'Article' do
  subject(:article) { Article.new(author: nil) }

  it 'indicates that the author is unknown' do
    expect(article.description).to include('by an unknown author')
  end
end

# good - with better object design
describe 'Article' do
  subject(:presenter) { ArticlePresenter.new(article) }
  let(:article) { Article.new }

  it 'indicates that the author is unknown' do
    allow(article).to receive(:author).and_return(nil)
    expect(presenter.description).to include('by an unknown author')
  end
end

# bad
it do
  # ...
end

specify 'it sends an email' do
  # ...
end

specify { is_expected.to be_truthy }

it '#do_something is deprecated' do
  ...
end

# good
specify do
  # ...
end

it 'sends an email' do
  # ...
end

it { is_expected.to be_truthy }

specify '#do_something is deprecated' do
  ...
end

# bad
[:new, :show, :index].each do |action|
  it 'returns 200' do
    get action
    expect(response).to be_ok
  end
end

# good - more verbose, but better for the future development
describe 'GET new' do
  it 'returns 200' do
    get :new
    expect(response).to be_ok
  end
end

describe 'GET show' do
  it 'returns 200' do
    get :show
    expect(response).to be_ok
  end
end

describe 'GET index' do
  it 'returns 200' do
    get :index
    expect(response).to be_ok
  end
end

# bad
it 'publishes the article' do
  article.publish

  # Creating another shared Article test object above would cause this
  # test to break
  expect(Article.count).to eq(2)
end

# good
it 'publishes the article' do
  expect { article.publish }.to change(Article, :count).by(1)
end

# bad
subject(:article) do
  Article.create(
    title: 'Piccolina',
    author: 'John Archer',
    published_at: '17 August 2172',
    approved: true
  )
end

# good
subject(:article) { FactoryBot.create(:article) }

# good
RSpec.describe User do
  describe ".top" do
    subject { described_class.top(2) }

    before { FactoryBot.create_list(:user, 3) }

    it { is_expected.to have(2).items }
  end
end

# good - verifying instance double
article = instance_double('Article')
allow(article).to receive(:author).and_return(nil)

presenter = described_class.new(article)
expect(presenter.title).to include('by an unknown author')


# good - verifying object double
article = object_double(Article.new, valid?: true)
expect(article.save).to be true


# good - verifying partial double
allow(Article).to receive(:find).with(5).and_return(article)


# good - verifying class double
notifier = class_double('Notifier')
expect(notifier).to receive(:notify).with('suspended as')

describe InvoiceReminder do
  subject(:time_with_offset) { described_class.new.get_offset_time }

  # bad
  it 'offsets the time 2 days into the future' do
    current_time = Time.now
    allow(Time).to receive(:now).and_return(current_time)
    expect(time_with_offset).to eq(current_time + 2.days)
  end

  # good
  it 'offsets the time 2 days into the future' do
    Timecop.freeze(Time.now) do
      expect(time_with_offset).to eq 2.days.from_now
    end
  end
end

# good
context 'with unauthorized access' do
  let(:uri) { 'http://api.lelylan.com/types' }

  before { stub_request(:get, uri).to_return(status: 401, body: fixture('401.json')) }

  it 'returns access denied' do
    page.driver.get uri
    expect(page).to have_content 'Access denied'
  end
end

# bad
describe SomeClass do
  CONSTANT_HERE = 'I leak into global namespace'
end

# good
describe SomeClass do
  before do
    stub_const('CONSTANT_HERE', 'I only exist during this example')
  end
end

# bad
describe SomeClass do
  class FooClass < described_class
    def double_that
      some_base_method * 2
    end
  end

  it { expect(FooClass.new.double_that).to eq(4) }
end

# good - anonymous class, no constant needs to be defined
describe SomeClass do
  let(:foo_class) do
    Class.new(described_class) do
      def double_that
        some_base_method * 2
      end
    end
  end

  it { expect(foo_class.new.double_that).to eq(4) }
end

# good - constant is stubbed
describe SomeClass do
  before do
    foo_class = Class.new(described_class) do
                  def do_something
                  end
                end
    stub_const('FooClass', foo_class)
  end

  it { expect(FooClass.new.double_that).to eq(4) }
end

# bad
subject { -> { do_something } }
it { is_expected.to change(something).to(new_value) }

# good
it 'changes something to a new value' do
  expect { do_something }.to change(something).to(new_value)
end

# bad - 'Summary user logged in no display name shows a placeholder'
describe 'Summary' do
 context 'user logged in' do
   context 'no display name' do
     it 'shows a placeholder' do
     end
   end
 end
end

# good - 'Summary when the user is logged in when the display name is blank shows a placeholder'
describe 'Summary' do
 context 'when the user is logged in' do
   context 'when the display name is blank' do
     it 'shows a placeholder' do
     end
   end
 end
end

# bad
it 'returns the display name if it is present' do
  # ...
end

# good
context 'when display name is present' do
  it 'returns the display name' do
    # ...
  end
end

# This encourages the addition of negative test cases that might have
# been overlooked
context 'when display name is not present' do
  it 'returns nil' do
    # ...
  end
end

# bad
it 'rewrites "should not return something" as "does not return something"' do
  # ...
end

# good
it 'rewrites "should not return something"' do
  expect(rewrite('should not return something')).to
    eq 'does not return something'
end

# good - self-documenting
specify do
  expect(rewrite('should not return something')).to
    eq 'does not return something'
end

# bad
it 'should return the summary' do
  # ...
end

# good
it 'returns the summary' do
  # ...
end

# bad
describe 'the authenticate method for User' do
  # ...
end

describe 'if the user is an admin' do
  # ...
end

# good
describe '.authenticate' do
  # ...
end

describe '#admin?' do
  # ...
end

# bad
it 'creates a resource' do
  response.should respond_with_content_type(:json)
end

# good
it 'creates a resource' do
  expect(response).to respond_with_content_type(:json)
end

describe Article do
  subject(:article) { FactoryBot.create(:article) }

  # bad
  it 'is published' do
    expect(article.published?).to be true
  end

  # good
  it 'is published' do
    expect(article).to be_published
  end

  # even better
  it { is_expected.to be_published }
end

# bad
it 'includes a title' do
  expect(article.title.include?('a lengthy title')).to be true
end

# good
it 'includes a title' do
  expect(article.title).to include 'a lengthy title'
end

# bad
it 'has author' do
  expect(article.author).to be
end

# good
it 'has author' do
  expect(article.author).to be_truthy # same as the original
  expect(article.author).not_to be_nil # `be` is often used to check for non-nil value
  expect(article.author).to be_an(Author) # explicit check for the type of the value
end

# bad
it 'returns JSON with temperature in Celsius' do
  json = JSON.parse(response.body).with_indifferent_access
  expect(json[:celsius]).to eq 30
end

it 'returns JSON with temperature in Fahrenheit' do
  json = JSON.parse(response.body).with_indifferent_access
  expect(json[:fahrenheit]).to eq 86
end

# good
it 'returns JSON with temperature in Celsius' do
  expect(response).to include_json(celsius: 30)
end

it 'returns JSON with temperature in Fahrenheit' do
  expect(response).to include_json(fahrenheit: 86)
end

# bad
it 'has a name' do
  allow_any_instance_of(User).to receive(:name).and_return('Tweedledee')
  expect(account.name).to eq 'Tweedledee'
end

# good
let(:account) { Account.new(user) }

it 'has a name' do
  allow(user).to receive(:name).and_return('Tweedledee')
  expect(account.name).to eq 'Tweedledee'
end

# bad
describe '#title' do
  it 'is required' do
    article.title = nil
    article.valid?
    expect(article.errors[:title])
      .to contain_exactly('Article has no title')
    not
  end
end

# good
describe '#title' do
  it 'is required' do
    expect(article).to validate_presence_of(:title)
      .with_message('Article has no title')
  end
end

# spec/views/articles/new.html.erb_spec.rb
describe 'articles/new.html.erb' do
  # ...
end

# spec/views/articles/edit.html.erb_spec.rb
describe 'articles/edit.html.erb' do
  it 'renders the form for a new article creation' do
    assign(:article, double(Article).as_null_object)
    render
    expect(rendered).to have_selector('form',
      method: 'post',
      action: articles_path
    ) do |form|
      expect(form).to have_selector('input', type: 'submit')
    end
  end
end

# bad
expect(page).to_not have_selector('input', type: 'submit')
expect(page).to_not have_xpath('tr')

# good
expect(page).to have_no_selector('input', type: 'submit')
expect(page).to have_no_xpath('tr')

# app/helpers/articles_helper.rb
class ArticlesHelper
  def formatted_date(date)
    # ...
  end
end

# app/views/articles/show.html.erb
<%= 'Published at: #{formatted_date(@article.published_at)}' %>

# spec/views/articles/show.html.erb_spec.rb
describe 'articles/show.html.erb' do
  it 'displays the formatted date of article publishing' do
    article = double(Article, published_at: Date.new(2012, 01, 01))
    assign(:article, article)

    allow(template).to_receive(:formatted_date).with(article.published_at).and_return('01.01.2012')

    render
    expect(rendered).to have_content('Published at: 01.01.2012')
  end
end

# Example of a commonly used controller spec
# spec/controllers/articles_controller_spec.rb
# We are interested only in the actions the controller should perform
# So we are mocking the model creation and stubbing its methods
# And we concentrate only on the things the controller should do

describe ArticlesController do
  # The model will be used in the specs for all methods of the controller
  let(:article) { double(Article) }

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

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

    it 'saves the article' do
      expect(article).to receive(:save)
      post :create
    end

    it 'redirects to the Articles index' do
      allow(article).to receive(:save)
      post :create
      expect(response).to redirect_to(action: 'index')
    end
  end
end

# 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) { double(Article) }

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

    it 'creates a new article with the given attributes' do
      expect(Article).to 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
      expect(article).to receive(:save)
      post :create
    end

    context 'when the article saves successfully' do
      before do
        allow(article).to receive(:save).and_return(true)
      end

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

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

    context 'when the article fails to save' do
      before do
        allow(article).to receive(:save).and_return(false)
      end

      it 'assigns @article' do
        post :create
        expect(assigns[:article]).to eq(article)
      end

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

describe Article do
  subject(:article) { FactoryBot.create(:article) }

  it { is_expected.to be_an Article }
  it { is_expected.to be_persisted }
end

describe Article do
  let(:article) { FactoryBot.create(:article) }
end

describe Article do
  it 'is valid with valid attributes' do
    expect(article).to be_valid
  end
end

# bad
describe '#title' do
  it 'is required' do
    article.title = nil
    expect(article).to_not be_valid
  end
end

# preferred
describe '#title' do
  it 'is required' do
    article.title = nil
    article.valid?
    expect(article.errors[:title].size).to eq(1)
  end
end

describe '#title' do
  it 'is required' do
    article.title = nil
    article.valid?
    expect(article.errors[:title].size).to eq(1)
  end
end

describe '#name' do
  it 'is required' do
    article.name = nil
    article.valid?
    expect(article.errors[:name].size).to eq(1)
  end
end

describe Article do
  describe '#title' do
    it 'is unique' do
      another_article = FactoryBot.create(:article, title: article.title)
      article.valid?
      expect(article.errors[:title].size).to eq(1)
    end
  end
end

describe SubscriberMailer do
  let(:subscriber) { double(Subscription, email: '[email protected]', name: 'John Doe') }

  describe 'successful registration email' do
    subject(:email) { SubscriptionMailer.successful_registration_email(subscriber) }

    it { is_expected.to have_attributes(subject: 'Successful Registration!', from: ['infor@your_site.com'], to: [subscriber.email]) }

    it 'contains the subscriber name' do
      expect(email.body.encoded).to match(subscriber.name)
    end
  end
end

# .rspec
--color
--require spec_helper

# .rspec-local
--profile 2