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Testing the Blog with RSpec

In the previous guide you added authentication to your blog application. If you haven’t run through that post then you should do so now before starting this one. If you feel confident with Rails but want to learn more about testing you can find some instructions on getting the code set up properly below.

Introduction to Automated Testing

One of the biggest advantages of Rails is the community focus on testing. The Ruby and Rails communities have put a great deal of effort into building first-class tools and methods for making sure our apps are as correct as possible. With tools like RSpec and Capybara, Ruby and Rails lead the way in developing easy to use and innovative tools to support widely embraced methods like Test Driven Development (TDD), Behaviour Driven Development (BDD) and Continuous Integration (CI).

Let’s dive into testing now.

Setup

Add the gem rspec-rails to the development and test group in your Gemfile so it looks like this: (Windows users, if you added it previously, don’t forget to keep the coffee-script-source gem in the list)

# Gemfile
source 'https://rubygems.org'

git_source(:github) do |repo_name|
  repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
  "https://github.com/#{repo_name}.git"
end

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 5.1.6'
# Use sqlite3 as the database for Active Record
gem 'sqlite3', group: [:development, :test]
gem 'pg', group: :production
# Use Puma as the app server
gem 'puma', '~> 3.7'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# See https://github.com/rails/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use devise for authentication
gem 'devise'

# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.2'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.5'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'

gem 'record_tag_helper', '~> 1.0'

# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development

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'
end

group :development do
  # Access an IRB console on exception pages or by using <%= console %> anywhere in the code.
  gem 'web-console', '>= 3.3.0'
  gem 'listen', '>= 3.0.5', '< 3.2'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

Save the file and run bundle install --without=production

This will add Rspec and RSpec Rails to our Rails application. RSpec is a commonly used TDD (and BDD) testing tool which provides a special testing language (powered by Ruby) for testing existing code and for informing developers about the structure and functionality of yet to be written code!

To complete the installation run:

rails generate rspec:install

rails generate rspec:model post

rails g rspec:model comment

rails g is the short version of this command, and can be used anytime you would use rails generate

Normally if you generate a Rails entity like a controller or model then this will automatically create a spec for you, but since we’ve already got a bunch of code that isn’t tested we have to manually generate a spec to test our comment model.

We can now run the specs we’ve generated. Run rails spec. Alternatively use the rspec command. You can run individual specs as follows:

rspec spec/models/post_spec.rb

Or all the model specs with: rspec spec/models. With this last example you’re providing a directory for rspec to run, it simply runs every spec it can find in that folder and all sub-folders.

Testing the Post

Our Post model seems fairly empty but there is already some business logic in there that we can test. Rails validations are considered business logic and are easy to test. Open spec/models/post_spec.rb and update it so that it looks like:

# spec/models/post_spec.rb
require 'rails_helper'

RSpec.describe Post, type: :model do
  it 'should validate presence of title' do
    post = Post.new
    post.valid?
    expect(post.errors.messages[:title]).to include "can't be blank"
  end
end

Once you’ve saved it, run rspec spec/models/post_spec.rb. The test should pass with 1 example, 0 failures. But we’re not done yet. Over the lifetime of our application we’ll probably be adding lots of extra functionality and our spec is very flat. We should organise it a litte better and structure it in such a way which also allows us to reuse code:

# spec/models/post_spec.rb
require 'rails_helper'

RSpec.describe Post, type: :model do
  describe 'validations' do
    subject(:post) { Post.new } # sets the subject of this describe block
    before { post.valid? }      # runs a precondition for the test/s

    [:title, :body].each do |attribute|
      it "should validate presence of #{attribute}" do
        expect(post.errors[attribute].size).to be >= 1
        expect(post.errors.messages[attribute]).to include "can't be blank"
      end
    end
  end
end

What we’re doing here is splitting up the test into a “validations” section and then declaring the subject of the test. The before block will invoke some common code to be run for each test and then each test just checks that there is an error on the model, and that the error is the expected error.

RSpec is a tool that provides a nice Domain Specific Language (DSL) to write specs. The important documentation to read is for expectations and matchers, but for the purposes of this project we’ll be providing and explaining most of the test code for you.

Since we’re writing a fully functional spec for code that is already written, we’ll need to make sure our test actually works by intentionally “breaking” some of our code. Open app/models/post.rb and comment out Line 5 so your Post model looks like:

# app/models/post.rb
class Post < ApplicationRecord
  has_many :comments, dependent: :destroy

  # validates :body, :title, presence: true
end

Once you’ve saved the file, you can rerun the spec with rspec spec/models/post_spec.rb. You should receive 2 examples, 2 failures and the error messages will be printed in your terminal. Be careful to read the error messages closely. When you’re done uncomment Line 5 in app/models/post.rb save the file and rerun the spec to ensure that everything is passing correctly.

We’ll also need to write a unit test for our comment model. Open spec/models/comment_spec.rb and update it to ensure that a comment will always belong to a post, and the comment will always have a body. The code to do this looks like:

# spec/models/comment_spec.rb
require 'rails_helper'

RSpec.describe Comment, type: :model do
  describe 'validations' do
    subject(:comment) { Comment.new }
    before { comment.valid? }

    it 'should validate presence of post' do
      expect(comment.errors[:post].size).to be >= 1
      expect(comment.errors.messages[:post]).to include "must exist"
    end

    it 'should validate presence of body' do
      expect(comment.errors[:body].size).to be >= 1
      expect(comment.errors.messages[:body]).to include "can't be blank"
    end
  end
end

When you run rspec spec/models/comment_spec.rb you’ll receive:

Failures:

Failures:

  1) Comment validations should validate presence of body
     Failure/Error: expect(comment.errors[:body].size).to be >= 1

       expected: >= 1
            got:    0
     # ./spec/models/comment_spec.rb:10:in `block (3 levels) in <top (required)>'

Finished in 0.04008 seconds (files took 1.4 seconds to load)
2 examples, 1 failure

If you open app/models/comment.rb you’ll notice that there aren’t any validations on our comment model. If you add validates :body, presence: true into the class so that it looks like:

# app/models/comment.rb
class Comment < ApplicationRecord
  belongs_to :post

  validates :body, presence: true
end

and re-run your spec you’ll see the test pass and “go green”.

Congratulations, you’ve just TDD’d your first piece of application logic! One of the amazing things about working with Rails there’s a very quick feedback loop between writing a failing test, making it pass and then suddenly having a complete functional feature in your application.

At this stage we’ve completed a small block of work, tests are passing (which you can check by running the spec command) so we should commit our work with: git add . and git commit -m "Added Rspec and first model specs"

We’re not done with our tests though.

Acceptance tests

Rails fully supports the concept of an acceptance test, which is a full-stack automated test that behaves exactly like someone opening a browser and clicking around your site. We’ll be using Capybara primarily with RackTest.

Setting up Capybara

As you probably expect by now we’ll be adding a new gem to our Gemfile. Open the Gemfile and add the following lines to the bottom:

group :test do
  gem 'capybara'
end

Then save the file and run bundle install --without=production to install the new gems. We only need Capybara for our tests, so we’re creating a section specifically to ensure that Capybara is only loaded when we run our tests.

Next open spec/rails_helper.rb (which was created when you installed spec) and add the following lines.

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

This tells spec/rails_helper.rb to include some special helper files that Capybara provides specifically for testing Rails applications.

Capybara also provides helper files for testing Rails Controllers, so we need to add the following lines to spec/rails_helper.rb:

RSpec.configure do |config|
  config.include Devise::Test::ControllerHelpers, type: :controller
  config.include Devise::Test::ControllerHelpers, type: :view
  config.include Devise::Test::IntegrationHelpers, type: :feature
  config.include Warden::Test::Helpers
end

(Don’t forget to save your file.)

Your spec file should now look like this:

# spec/rails_helper.rb
# This file is copied to spec/ when you run 'rails generate rspec:install'
ENV['RAILS_ENV'] ||= 'test'
require File.expand_path('../../config/environment', __FILE__)
# Prevent database truncation if the environment is production
abort("The Rails environment is running in production mode!") if Rails.env.production?
require 'spec_helper'
require 'rspec/rails'
# Add additional requires below this line. Rails is not loaded until this point!
require 'capybara/rails'
require 'capybara/rspec'

RSpec.configure do |config|
  config.include Devise::Test::ControllerHelpers, type: :controller
  config.include Devise::Test::ControllerHelpers, type: :view
  config.include Devise::Test::IntegrationHelpers, type: :feature
  config.include Warden::Test::Helpers
end

# Requires supporting ruby files with custom matchers and macros, etc, in
# spec/support/ and its subdirectories. Files matching `spec/**/*_spec.rb` are
# run as spec files by default. This means that files in spec/support that end
# in _spec.rb will both be required and run as specs, causing the specs to be
# run twice. It is recommended that you do not name files matching this glob to
# end with _spec.rb. You can configure this pattern with the --pattern
# option on the command line or in ~/.rspec, .rspec or `.rspec-local`.
#
# The following line is provided for convenience purposes. It has the downside
# of increasing the boot-up time by auto-requiring all files in the support
# directory. Alternatively, in the individual `*_spec.rb` files, manually
# require only the support files necessary.
#
# Dir[Rails.root.join('spec/support/**/*.rb')].each { |f| require f }

# Checks for pending migration and applies them before tests are run.
# If you are not using ActiveRecord, you can remove this line.
ActiveRecord::Migration.maintain_test_schema!

RSpec.configure do |config|
  # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
  config.fixture_path = "#{::Rails.root}/spec/fixtures"

  # If you're not using ActiveRecord, or you'd prefer not to run each of your
  # examples within a transaction, remove the following line or assign false
  # instead of true.
  # config.use_transactional_fixtures = true
  config.use_transactional_fixtures = false

  # RSpec Rails can automatically mix in different behaviours to your tests
  # based on their file location, for example enabling you to call `get` and
  # `post` in specs under `spec/controllers`.
  #
  # You can disable this behaviour by removing the line below, and instead
  # explicitly tag your specs with their type, e.g.:
  #
  #     RSpec.describe UsersController, :type => :controller do
  #       # ...
  #     end
  #
  # The different available types are documented in the features, such as in
  # https://relishapp.com/rspec/rspec-rails/docs
  config.infer_spec_type_from_file_location!

  # Filter lines from Rails gems in backtraces.
  config.filter_rails_from_backtrace!
  # arbitrary gems may also be filtered via:
  # config.filter_gems_from_backtrace("gem name")
end

Next we’ll create our first acceptance test.

The first acceptance test

Create a folder called spec/features then create a file spec/features/reading_blog_spec.rb with the following contents:

# spec/features/reading_blog_spec.rb
require 'rails_helper'

feature 'Reading the Blog' do
  background do
    Post.destroy_all
    @post = Post.create(title: 'Awesome Blog Post', body: 'Lorem ipsum dolor sit amet')
    Post.create(title: 'Another Awesome Post', body: 'Lorem ipsum dolor sit amet')
    @user = User.create
    sign_in @user
  end

  scenario 'Reading the blog index' do
    visit root_path

    expect(page).to have_content 'Awesome Blog Post'
    expect(page).to have_content 'Another Awesome Post'
  end

  scenario 'Reading an individual blog' do
    visit root_path
    click_link 'Awesome Blog Post'

    expect(current_path).to eq post_path(@post)
  end
end

Save this file and run it with: rspec spec/features. You should get 2 examples, 0 failures. But once again there’s a problem. We’ve written a test which passes immediately, we should make it fail to check that the test is actually checking what we want it to check. We’ll open app/views/posts/_post.html.erb and alter the Post titles as follows:

<h2><%= link_to_unless_current 'Blog Post', post %></h2>
<%= simple_format post.body %>

(Don’t forget to save your file.)

Now when you rerun the spec (rspec spec/features) you’ll receive two errors:

Failure/Error: expect(page).to have_content 'Awesome Blog Post'
  expected to find text "Awesome Blog Post"

Failure/Error: click_link 'Awesome Blog Post'
     Capybara::ElementNotFound:
       Unable to find link "Awesome Blog Post"

Undo your changes to app/views/posts/_post.html.erb so that it once again looks like:

<h2><%= link_to_unless_current post.title, post %></h2>
<%= simple_format post.body %>

Save your changes and rerun your spec to make sure everything is okay.

Writing more Acceptance Tests

Acceptance tests are really powerful since they are a high level description of how your application should function. By writing acceptance tests it’s entirely possible to build an entire user-facing feature without opening your web-browser! But more importantly, it gives you a high level of confidence that a feature will work, and won’t inadvertantly break if you make changes elsewhere.

We’re going to make more acceptance tests now.

Create a file: spec/features/post_comments_spec.rb with the contents:

# spec/features/post_comments_spec.rb
require 'rails_helper'

RSpec.feature "Posting Comments", :type => :feature do
  background do
    @post = Post.create(title: 'Awesome Blog Post', body: 'Lorem ipsum dolor sit amet')
  end

  scenario "Visit root_path" do
    @user = User.create(email:'test@example.com', password: 'secret')

    visit new_user_session_path
    fill_in 'Email', with: @user.email
    fill_in 'Password', with: @user.password
    click_button 'Log in'

    visit post_path(@post)

    comment = 'This post is just filler text. Ripped off!'

    fill_in 'comment_body', with: comment
    click_button 'Add comment'

    expect(page).to have_content comment
  end
end

Save that, then create a file: spec/features/managing_posts_spec.rb with the contents:

# spec/features/managing_posts_spec.rb
require 'rails_helper'

RSpec.feature 'Managing Posts', :type => :feature do

  scenario 'Guests cannot create posts' do
    visit root_path
    click_link 'New Post'

    expect(page).to have_content 'Sign up | Login'
  end

  scenario 'Posting a new blog' do
    @user = User.create(email:'test@example.com', password: 'secret')

    visit new_user_session_path
    fill_in 'Email', with: @user.email
    fill_in 'Password', with: @user.password
    click_button 'Log in'

    visit root_path

    click_link 'New Post'

    expect(page).to have_content 'New Post'

    fill_in 'Title', with: 'I love cheese'
    fill_in 'Body', with: "It's pretty amazing, don't you think?"

    click_button 'Create Post'
    expect(page).to have_content 'I love cheese'
  end

  context 'with an existing blog post' do
    background do
      @post = Post.create(title: 'Awesome Blog Post', body: 'Lorem ipsum dolor sit amet')
    end

    scenario 'Editing an existing blog' do
      @user = User.create(email:'test@example.com', password: 'secret')

      visit new_user_session_path
      fill_in 'Email', with: @user.email
      fill_in 'Password', with: @user.password
      click_button 'Log in'

      visit post_path(@post)

      page.driver.browser.authorize 'admin', 'secret'
      click_link 'Edit'

      fill_in 'Title', with: 'Not really Awesome Blog Post'
      click_button 'Update Post'

      expect(page).to have_content 'Not really Awesome Blog Post'
    end
  end
end

Save that file. Now let’s run all of our acceptance/feature specs. Open your terminal and run: rspec spec/features. If everything has worked you’ll get something like:

......

Finished in 0.26705 seconds
6 examples, 0 failures

Cleaning up

We’ve now tested our application with some unit tests of our models, and using acceptance tests. We’ve increased our confidence in our existing code and we’re ready to move on to adding extra features to our blog. Before we do that though we should run all our tests and commit our code.

To run all your tests either run rake spec or rspec. Rake is a utility command which provides a common interface for interacting with your application. the spec task simply runs rspec internally. Once your tests have finished running (and they all pass!) you should commit your code. Run:

git add .
git commit -m "Adding capybara and tests for existing functionality"

Next Steps

Up next we’re going to go more in depth with Rails and begin to add more features to the blogging engine. Head on over to Part 4: Finishing a Basic Blog to get started.

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