Testing Rails with RSpec

Beginners introduction to testing Ruby On Rails application with RSpec and Capybara.

Install Rails with RSpec (v0.1)

1. Install rails without minitest: rails new rails-rspec-tutorial -T;

2. Add rspec to Gemfile:

  group :development, :test do
    gem 'rspec-rails', '~> 3.7'
  end

3. Install dependencies: bundle install;

4. Execute bundle exec rails generate rspec:install to create a /spec dir;

5. Run rspec: bundle exec rspec

Your first spec (v0.2)

1. Create first spec:

require "rails_helper"

RSpec.describe "hello spec" do
  describe "math" do
    expect(6 * 7).to eq(43)
  end
end

2. And catch an error:

Failures:

  1) hello spec math should be able to perform basic math
     Failure/Error: expect(6 * 7).to eq(43)
     
       expected: 43
            got: 42

3. Fix the error to get test passed:

require "rails_helper"

RSpec.describe "hello spec" do
  describe "math" do
    it "should be able to perform basic math" do
      # expect(6 * 7).to eq(43) # => false
      expect(6 * 7).to eq(42)
    end
  end
end

4. Add another spec with empty string:

require "rails_helper"

RSpec.describe "hello spec" do
  # ...
  describe String do
    let(:string) { String.new }
    it "should provide an empty string" do
      expect(string).to eq("")
    end
  end
end

Create a unit test for Article model (v0.3)

1. Create model Article:

bundle exec rails g model Article title:string body:text active:boolean

RAILS_ENV=test bundle exec rake db:migrate

2. Create spec/models/article_spec.rb:

require "rails_helper"

RSpec.describe Article, type: :model do
  context "validations tests" do
    it "ensures the title is present" do
      article = Article.new(body: "Content of the body")
      expect(article.valid?).to eq(false)
    end

    it "ensures the body is present" do
      article = Article.new(title: "Title")
      expect(article.valid?).to eq(false)
    end

    it "ensures the article is active by default" do
      article = Article.new(body: "Content of the body", title: "Title")
      expect(article.active?).to eq(true)
    end

    it "should be able to save article" do
      article = Article.new(body: "Content of the body", title: "Title")
      expect(article.save).to eq(true)
    end
  end

  context "scopes tests" do

  end
end

3. Add some presence validators to app/models/article.rb:

class Article < ApplicationRecord
  validates_presence_of :title, :body
end

4. Create a migration:

class MakeArticleActiveByDefault < ActiveRecord::Migration[5.1]
  def change
    change_column :articles, :active, :boolean, default: true
  end
end

5. Run migration:

bundle exec rake db:migrate

6. Add scope specs:

require "rails_helper"

RSpec.describe Article, type: :model do
  # ...

  context "scopes tests" do
    let(:params) { { body: "Content of the body", title: "Title", active: true } }
    before(:each) do
      Article.create(params)
      Article.create(params)
      Article.create(params)
      Article.create(params.merge(active: false))
      Article.create(params.merge(active: false))
    end

    it "should return all active articles" do
      expect(Article.active.count).to eq(3)
    end

    it "should return all inactive articles" do
      expect(Article.inactive.count).to eq(2)
    end
  end
end

Create functional test for Articles controller (v0.4)

1. Create Articles controller scaffold:

bundle exec rails g scaffold_controller Articles

rm -rf spec/views spec/routing spec/request spec/helpers spec/requests

2. Create Articles spec:

require "rails_helper"

RSpec.describe ArticlesController, type: :controller do
  context "GET #index" do
    it "returns a success response" do
      get :index
      # expect(response.success).to eq(true)
      expect(response).to be_success
    end
  end

  context "GET #show" do
    let!(:article) { Article.create(title: "Test title", body: "Test body") }
    it "returns a success response" do
      get :show, params: { id: article }
      expect(response).to be_success
    end
  end
end

3. Add articles to routes.rb file:

Rails.application.routes.draw do
  resources :articles
end

4. Add --format documentation to .rspec

Create integration spec and a home page (v0.5)

1. Add Capybara to Gemfile:

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
  gem 'rspec-rails', '~> 3.7'
  gem 'capybara'
end

2. Add these lines to your spec/rails_helper.rb file:

require 'capybara/rails'
require 'capybara/rspec'

3. Create first feature test by running bundle exec rails g rspec:feature home_page:

require "rails_helper"

RSpec.feature "Visiting the homepage", type: :feature do
  scenario "The visitor should see a welcome message" do
    visit root_path
    expect(page).to have_text("Welcome to my blog!")
  end
end

4. Add root to routes.rb:

Rails.application.routes.draw do
  root "home#index"
  resources :articles
end

5. Generate controller:

bundle exec rails g controller Home index

rm -rf spec/controllers/home_controller_spec.rb spec/views/home spec/views/home/index.html.erb_spec.rb spec/helpers/home_helper_spec.rb

6. Modify the view app/views/home/index.html.erb:

<h1>Welcome to my blog!</h1>
<p>Find me in app/views/home/index.html.erb</p>

Create integration spec for Articles v0.6

1. bundle exec rails g rspec:feature articles

2. Create feature spec:

require 'rails_helper'

RSpec.feature "Articles", type: :feature do
  context "Create new article" do
    scenario "Should be successful" do
      visit new_article_path
      within("form") do
        fill_in "Title", with: "Test title"
        fill_in "Body", with: "Test body"
        check "Active"
      end
      click_button "Create Article"
      expect(page).to have_content("Article successfully created")
    end

    scenario "Should fail" do

    end
  end

  context "Update article" do

  end

  context "Remove existing article" do

  end
end

3. Fix the view (app/views/articles/_form.erb):

<%= form_with(model: article, local: true) do |form| %>
  <% if article.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(article.errors.count, "error") %> prohibited this article from being saved:</h2>

      <ul>
      <% article.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div>
    <%= form.label :title %> 
    <%= form.text_field :title, id: "article_title" %> 
  </div>

  <div>
    <%= form.label :body %> 
    <%= form.text_area :body, id: "article_body" %> 
  </div>

  <div>
    <%= form.label :active %> 
    <%= form.check_box :active, id: "article_active" %> 
  </div>

  <div class="actions">
    <%= form.submit %>
  </div>
<% end %>

4. Allow attributes in app/controllers/articles_controller.rb:

def article_params
  params.require(:article).permit(:active, :id, :title, :body)
end

5. Full Articles test:

require 'rails_helper'

RSpec.feature "Articles", type: :feature do
  context "Create new article" do
    before(:each) do
      visit new_article_path
      within("form") do
        fill_in "Title", with: "Test title"
        check "Active"
      end
    end

    scenario "should be successful" do
      fill_in "Body", with: "Test body"
      click_button "Create Article"
      expect(page).to have_content("Article was successfully created")
    end

    scenario "should fail" do
      click_button "Create Article"
      expect(page).to have_content("Body can't be blank")
    end
  end

  context "Update article" do
    let(:article) { Article.create(title: "Test title", body: "Test content") }
    before(:each) do
      visit edit_article_path(article)
    end

    scenario "should be successful" do
      within("form") do
        fill_in "Body", with: "New body content"
      end
      click_button "Update Article"
      expect(page).to have_content("Article was successfully updated")
    end

    scenario "should fail" do
      within("form") do
        fill_in "Body", with: ""
      end
      click_button "Update Article"
      expect(page).to have_content("Body can't be blank")
    end
  end

  context "Remove existing article" do
    let!(:article) { Article.create(title: "Test title", body: "Test content") }
    scenario "remove article" do
      visit articles_path
      click_link "Destroy"
      expect(page).to have_content("Article was successfully destroyed")
      expect(Article.count).to eq(0)
    end
  end
end

Add Selenium web driver (v0.7):

1. Add to Gemfile:

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
  gem 'rspec-rails', '~> 3.7'
  gem 'capybara'
  gem 'selenium-webdriver'
end

2. Add to spec/rspec_helper.rb:

Capybara.default_driver = :selenium_chrome_headless

3. Fix articles spec:

context "Remove existing article" do
  let!(:article) { Article.create(title: "Test title", body: "Test content") }
  scenario "remove article" do
    visit articles_path
    expect(Article.count).to eq(1)
    accept_alert do
      click_link "Destroy"
    end
    expect(page).to have_content("Article was successfully destroyed")
    expect(Article.count).to eq(0)
  end
end

Add simplecov gem (v0.8):

1. Rails coverage report: bundle exec rails stats

2. To install codecov add to your Gemfile:

gem 'simplecov', require: false, group: :test

3. Add to your spec/rails_helper.rb:

require 'simplecov'
SimpleCov.start

4. Don't forget to add coverage/ dir to your .gitignore file;

Helpful links:

• https://relishapp.com/rspec/rspec-rails/docs

• https://github.com/teamcapybara/capybara

• https://github.com/colszowka/simplecov

• http://www.betterspecs.org/

• https://github.com/thoughtbot/factory_bot

• https://github.com/ffaker/ffaker