Testing Rails with RSpec

Beginners introduction to testing Ruby On Rails application with RSpec and Capybara. Prior to using this tutorial make sure rspec is installed.

Your first spec

1. Create first spec spec/example/first_spec.rb:

require "rails_helper"

RSpec.describe "The math below is wrong..." do
  it "should equal 42 but we said 43" 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 "The math below is right..." do
  it "should equal 42" do
    expect(6 * 7).to eq(42)
  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 Project model

1. Create spec/models/project_spec.rb:

require "rails_helper"

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

    it "ensures the description is present" do
      project = Project.new(title: "Title")
      expect(project.valid?).to eq(false)
    end
    
    it "should be able to save project" do
      project = Project.new(title: "Title", description: "Some description content goes here")
      expect(project.save).to eq(true)
    end
  end

  context "scopes tests" do

  end
end

These tests should fail because the project is missing presence validators.

2. Add some presence validators to app/models/project.rb:

class Project < ApplicationRecord
  validates_presence_of :title, :description
end

Re-run the RSpec tests and the failing tests should now pass.

3. Add scope specs:

require "rails_helper"

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

  context "scopes tests" do
    let(:params) { { title: "Title", description: "some description" } }
    before(:each) do
      Project.create(params)
      Project.create(params)
      Project.create(params)
    end

    it "should return all projects" do
      expect(Project.count).to eq(3)
    end

  end
end

Create functional test for Projects controller

1. Create Projects spec spec/controller/projects_spec.rb:

require "rails_helper"

RSpec.describe ProjectsController, 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_successful
    end
  end

  context "GET #show" do
    let!(:project) { Project.create(title: "Test title", description: "Test description") }
    it "returns a success response" do
      get :show, params: { id: project }
      expect(response).to be_successful
    end
  end
end

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

1. Add Capybara to Gemfile:

group :development, :test do
  gem 'capybara'
end

2. 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 projects" do
    visit root_path
    expect(page).to have_text("Projects")
  end
end

Create integration spec for Projects

1. bundle exec rails g rspec:feature projects

2. Full Projects test:

require 'rails_helper'

RSpec.feature "Projects", type: :feature do
  context "Create new project" do
    before(:each) do
      visit new_project_path
      within("form") do
        fill_in "Title", with: "Test title"
      end
    end

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

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

  context "Update project" do
    let(:project) { Project.create(title: "Test title", description: "Test content") }
    before(:each) do
      visit edit_project_path(project)
    end

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

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

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

Add simplecov gem:

1. Rails coverage report: bundle exec rails stats

2. To install simplecov add to your Gemfile to the :test group:

gem 'simplecov', require: false

3. Add to your spec/rails_helper.rb:

require 'simplecov'
SimpleCov.start 'rails' do
  add_filter '/bin/'
  add_filter '/db/'
  add_filter '/spec/' # for rspec
end

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

5. Running bundle exec rspec will generate a coverage report

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