Setup Rspec, factory bot and database cleaner for Rails 5.2.6

Let’s find out how to configure a best test suite in Rails by using Rspec framwork and the other libraries that support rspec for writing smooth tests. We will be removing rails native test folder and other configurations.

For that we will be using Rspec, Factory bot for factories, Database cleaner.

Lets start from adding these gems into our Gemfile

group :development, :test do
  # Rspec testing module and needed libs
  gem 'factory_bot_rails', '5.2.0'
  gem 'rspec-rails', '~> 4.0.0'
end

group :test do
  # db cleaner for test suite 
  gem 'database_cleaner-active_record', '~> 2.0.1'
end

Now do

bunde install # this installs all the above gems

If you have already built the Rails app, your app may contain Rails own test suite. Remove the native rails test suite to add Rspec module to your project.

We use Rspec over rails native test module because rspec provides better helpers and machnism than Rails native test.

in application.rb file comment the following line

# require 'rails/test_unit/railtie'

inside the class Application add this line:

# Don't generate system test files.
config.generators.system_tests = nil

Remove the native rails test folder:

rm -r test/

We use factories over fixtures. Remove this line from rails_helper.rb

config.fixture_path = "#{::Rails.root}/spec/fixtures"

and modify this line to:

config.use_transactional_fixtures = false # instead of true

This is for preventing rails to generate the native test files when we run rails generators.

Database Cleaner

Now we configure the database cleaner that is used for managing data in our test cycles.

Open rails_helper.rb file and require that module

require 'rspec/rails'
require 'database_cleaner'  # <= add here

Note: Use only if you run integration tests with capybara or dealing with javascript codes in the test suite.

“Capybara spins up an instance of our Rails app that can’t see our test data transaction so even tho we’ve created a user in our tests, signing in will fail because to the Capybara run instance of our app, there are no users.”

I experienced database credentials issues:

➜ rspec
An error occurred while loading ./spec/models/user_spec.rb.
Failure/Error: ActiveRecord::Migration.maintain_test_schema!

Mysql2::Error::ConnectionError:
  Access denied for user 'username'@'localhost' (using password: NO)

First I thought of using database cleaner, later I realised that this error is because of my credentials.yml.enc file was corrupted somehow. I don’t know how that happend. So try to edit and see your credentials still exists in this file.

EDITOR="code --wait" bin/rails credentials:edit

Now in the Rspec configuration block we do the Database Cleaner configuration.

Add the following file:

spec/support/database_cleaner.rb

Inside, add the following:

# DB cleaner using database cleaner library
RSpec.configure do |config|
  # This says that before the entire test suite runs, clear 
  # the test database out completely
  config.before(:suite) do
    DatabaseCleaner.strategy = :transaction
    DatabaseCleaner.clean_with(:truncation)
  end

  # This sets the default database cleaning strategy to 
  # be transactions
  config.before(:each) do
    DatabaseCleaner.strategy = :transaction
  end

  # include this if you uses capybara integration tests
  config.before(:each, :js => true) do
    DatabaseCleaner.strategy = :truncation
  end

  # These lines hook up database_cleaner around the beginning 
  # and end of each test, telling it to execute whatever 
  # cleanup strategy we selected
  config.before(:each) do
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end
end

and be sure to require this file in rails_helper.rb

require 'rspec/rails'
require 'database_cleaner'
require_relative 'support/database_cleaner'  # <= here

Configure Factories

Note: We use factories over fixtures because factories provide better features that make writing test cases an easy task.

Create a folder to generate the factories:

mkdir spec/factories

Rails generators will automatically generate factory files for models inside this folder.

A generator for model automatically creating the following files:

spec/models/model_spec.rb
spec/factories/model.rb

Now lets load Factory bot configuration to rails test suite.

Add the following file:

spec/support/factory_bot.rb

and be sure to require this file in rails_helper.rb

require 'rspec/rails'
require 'database_cleaner'
require_relative 'support/database_cleaner'
require_relative 'support/factory_bot'  # <= here

You can see the following line commented

# Dir[Rails.root.join('spec', 'support', '**', '*.rb')].sort.each { |f| require f }

You can uncomment it to make all the factories available in your test suite. But I don’t recommend that to load all the files. We will be loading each factory whenver it is necessary.

Final rails_helper.rb file. We won’t use capybara for integration tests. So we are not adding database_cleaner configuration.

# This file is copied to spec/ when you run 'rails generate rspec:install'
require 'spec_helper'
ENV['RAILS_ENV'] ||= 'test'
require File.expand_path('../config/environment', __dir__)
# Prevent database truncation if the environment is production
abort('The Rails environment is running in production mode!') if Rails.env.production?
require 'rspec/rails'
require_relative 'support/factory_bot'

# Checks for pending migrations and applies them before tests are run.
# If you are not using ActiveRecord, you can remove these lines.
begin
  ActiveRecord::Migration.maintain_test_schema!
rescue ActiveRecord::PendingMigrationError => e
  puts e.to_s.strip
  exit 1
end
RSpec.configure do |config|
  # 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 = false

  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

A spec directory look something like this:

spec/
  controllers/
    user_controller_spec.rb
    product_controller_spec.rb
  factories/
    user.rb
    product.rb
  models/
    user_spec.rb
    product_spec.rb
  mailers/
    mailer_spec.rb
  services/
    service_spec.rb  
  rails_helper.rb
  spec_helper.rb

References:

https://github.com/rspec/rspec-rails
https://relishapp.com/rspec/rspec-rails/docs
https://github.com/thoughtbot/factory_bot/blob/master/GETTING_STARTED.md#configure-your-test-suite
https://github.com/DatabaseCleaner/database_cleaner

Model Specs

Lets generate a model spec. A model spec is used to test smaller parts of the system, such as classes or methods.

# RSpec also provides its own spec file generators
➜ rails generate rspec:model user
      create  spec/models/user_spec.rb
      invoke  factory_bot
      create    spec/factories/users.rb

Now run the rpsec command. That’s it. You can see the output from rspec.

➜ rspec
*

Pending: (Failures listed here are expected and do not affect your suite's status)

  1) Item add some examples to (or delete) /home/.../spec/models/user_spec.rb
     # Not yet implemented
     # ./spec/models/user_spec.rb:4

Finished in 0.00455 seconds (files took 1.06 seconds to load)
1 example, 0 failures, 1 pending

Lets discuss how to write a perfect model spec in the next lesson.

Author: Abhilash

Hey! This is Abhilash - A Ruby developer for years, specialised on web development, working as a freelance Ruby Developer. I have experience in other frameworks such as Angular, Sinatra, Laravel etc. Mainly working on Ruby On Rails platform since 2010. This blog is about Ruby, Ruby On Rails and other subjects where I have had a chance to work on. You can contact me here: abhilash.amballur@gmail.com Abhilash AK

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