My Rails setup (a work in progress)

template.rb

gem_group :development, :test do
  # Great Ruby dubugging companion: pretty print Ruby objects to visualize
  # their structure.
  # https://github.com/awesome-print/awesome_print
  # DOC: http://www.rubyinside.com/awesome_print-a-new-pretty-printer-for-your-ruby-objects-3208.html
  gem 'awesome_print',            '1.8.0'

  # Detects security vulnerabilities in RoR applications via static analysis
  # https://github.com/presidentbeef/brakeman
  # CHANGELOG: https://github.com/presidentbeef/brakeman/blob/master/CHANGES.md
  gem 'brakeman',                 '4.3.1', require: false

  # Patch-level verification for Bundled apps.
  # https://github.com/rubysec/bundler-audit
  # CHANGELOG: https://github.com/rubysec/bundler-audit/blob/master/ChangeLog.md
  gem 'bundler-audit',            '0.6.0'

  # Byebug is a Ruby debugger. Call 'byebug' anywhere in the code to stop
  # execution and get a debugger console
  # https://github.com/deivid-rodriguez/byebug
  # CHANGELOG: https://github.com/deivid-rodriguez/byebug/blob/master/CHANGELOG.md
  gem 'byebug',                   '10.0.2'

  # Adds support for Capybara system testing and selenium driver
  # https://github.com/teamcapybara/capybara
  # CHANGELOG: https://github.com/teamcapybara/capybara/blob/master/History.md
  gem 'capybara',                 '3.6.0'

  # Automatically save screenshots when a Capybara scenario fails.
  # https://github.com/mattheworiordan/capybara-screenshot
  # CHANGELOG: https://github.com/mattheworiordan/capybara-screenshot/blob/master/CHANGELOG.md
  gem 'capybara-screenshot',      '1.0.21'

  # Easy installation and use of chromedriver, the Chromium project's selenium
  # webdriver adapter.
  # https://github.com/flavorjones/chromedriver-helper
  # CHANGELOG: https://github.com/flavorjones/chromedriver-helper/blob/master/CHANGELOG.md
  gem 'chromedriver-helper',      '1.2.0'

  # Easily manage your environment, useful during testing.
  # https://github.com/thoughtbot/climate_control
  # SOURCE: https://robots.thoughtbot.com/testing-and-environment-variables
  gem 'climate_control', '0.2.0'

  # Fixtures replacement with a straightforward definition syntax
  # https://github.com/thoughtbot/factory_bot_rails
  # CHANGELOG: https://github.com/thoughtbot/factory_bot_rails/blob/master/NEWS
  gem 'factory_bot_rails',        '4.11.0'

  # Automatically generate an entity-relationship diagram (ERD) for your Rails
  # models.
  # https://github.com/voormedia/rails-erd
  # CHANGELOG: https://github.com/voormedia/rails-erd/blob/master/CHANGES.md
  gem 'rails-erd',                '1.5.2', require: false

  # Automatic Ruby code style checking tool. Aims to enforce the
  # community-driven Ruby Style Guide
  # https://github.com/bbatsov/rubocop
  # CHANGELOG: https://github.com/bbatsov/rubocop/blob/master/CHANGELOG.md
  gem 'rubocop',                  '0.58.2', require: false

  # Code style checking for RSpec files. A plugin for the RuboCop code style
  # enforcing & linting tool.
  #
  # CHANGELOG:
  gem 'rubocop-rspec',            '1.28.0', require: false

  # Testing framework for Rails
  # https://github.com/rspec/rspec-rails
  # CHANGELOG: https://github.com/rspec/rspec-rails/blob/master/Changelog.md
  gem 'rspec-rails',              '3.8.0'

  # WebDriver is a tool for writing automated tests of websites. It aims to
  # mimic the behaviour of a real user, and as such interacts with the HTML of
  # the application
  # https://github.com/SeleniumHQ/selenium/tree/master/rb
  # CHANGELOG: https://github.com/SeleniumHQ/selenium/blob/master/rb/CHANGES
  gem 'selenium-webdriver',       '3.14.0'

  # Shoulda Matchers provides RSpec- and Minitest-compatible one-liners that
  # test common Rails functionality. These tests would otherwise be much longer,
  # more complex, and error-prone.
  # https://github.com/thoughtbot/shoulda-matchers
  # CHANGELOG: https://github.com/thoughtbot/shoulda-matchers/blob/master/NEWS.md
  gem 'shoulda-matchers',         '3.1.2'

  # Code coverage for Ruby with a powerful configuration library and automatic
  # merging of coverage across test suites
  # https://github.com/colszowka/simplecov
  # CHANGELOG: https://github.com/colszowka/simplecov/blob/master/CHANGELOG.md
  gem 'simplecov',                '0.16.1', require: false

  # A gem providing "time travel" and "time freezing" capabilities, making it
  # dead simple to test time-dependent code.
  # https://github.com/travisjeffery/timecop
  # CHANGELOG: https://github.com/travisjeffery/timecop/blob/master/History.md
  gem 'timecop',                  '0.9.1'

  # WebMock allows stubbing HTTP requests and setting expectations on HTTP
  # requests.
  # https://github.com/bblimke/webmock
  # CHANGELOG: https://github.com/bblimke/webmock/blob/master/CHANGELOG.md
  gem 'webmock',                  '3.4.2'
end

gem_group :development do
  # Help to kill N+1 queries and unused eager loading.
  # https://github.com/flyerhzm/bullet
  # CHANGELOG: https://github.com/flyerhzm/bullet/blob/master/CHANGELOG.md
  gem 'bullet',                   '5.7.6'

  # A command line tool to easily handle events on file system modifications
  # https://github.com/guard/guard
  # CHANGELOG: https://github.com/guard/guard/releases
  gem 'guard',                    '2.14.2'

  # Automatically run your specs
  # https://github.com/guard/guard-rspec
  gem 'guard-rspec',              '4.7.3', require: false

  # Automatically checks Ruby code style with RuboCop when files are modified
  # https://github.com/yujinakayama/guard-rubocop
  # CHANGELOG: https://github.com/yujinakayama/guard-rubocop/blob/master/CHANGELOG.md
  gem 'guard-rubocop',            '1.3.0'

  # Automatically runs shell commands when watched files are modified
  # https://github.com/hawx/guard-shell
  gem 'guard-shell',              '0.7.1'

  # The Listen gem listens to file modifications and notifies you about the
  # changes (installed by Rails 5)
  # DOC: http://weblog.rubyonrails.org/2015/11/11/snappier-development-mode-in-rails-5/
  # https://github.com/guard/listen
  # CHANGELOG: https://github.com/guard/listen/releases
  gem 'listen',                   '3.1.5'

  # Use Pry as your rails console
  # https://github.com/rweng/pry-rails
  gem 'pry-rails',                '0.3.6'

  # Profiling toolkit for Rack applications with Rails integration. Client Side
  # profiling, DB profiling and Server profiling.
  # https://miniprofiler.com/
  # CHANGELOG: https://github.com/MiniProfiler/rack-mini-profiler/blob/master/CHANGELOG.md
  gem 'rack-mini-profiler',       '1.0.0'

  # Spring speeds up development by keeping your application running in the
  # background
  # https://github.com/rails/spring
  # CHANGELOG: https://github.com/rails/spring/blob/master/CHANGELOG.md
  gem 'spring',                   '2.0.2'
  gem 'spring-watcher-listen',    '2.0.1'

  # Access an IRB console on exception pages or by using <%= console %> anywhere
  # in the code
  # https://github.com/rails/web-console
  # CHANGELOG: https://github.com/rails/web-console/blob/master/CHANGELOG.markdown
  gem 'web-console',              '3.6.2'
end