Upgrade Rails to version 5.2.1 and adopt code & specs where necessary

Signed-off-by: Sebastian Serth <Sebastian.Serth@student.hpi.de>

config/initializers/application_controller_renderer.rb

@@ -0,0 +1,8 @@
+# Be sure to restart your server when you modify this file.
+
+# ActiveSupport::Reloader.to_prepare do
+#   ApplicationController.renderer.defaults.merge!(
+#     http_host: 'example.org',
+#     https: false
+#   )
+# end

config/initializers/assets.rb

@@ -1,12 +1,17 @@
 # Be sure to restart your server when you modify this file.
 
-# Version of your assets, change this if you want to expire all your assets.
-Rails.application.config.assets.version = '1.0'
+Rails.application.config.tap do |config|
 
-# Add additional assets to the asset load path
-# Rails.application.config.assets.paths << Emoji.images_path
+  # Version of your assets, change this if you want to expire all your assets.
+  config.assets.version = '1.0'
 
-# Precompile additional assets.
-# application.js, application.css, and all non-JS/CSS in app/assets folder are already added.
-# Rails.application.config.assets.precompile += %w( search.js )
-Rails.application.config.assets.precompile += %w( markdown-buttons.png )
+  # Add additional assets to the asset load path.
+  # config.assets.paths << Emoji.images_path
+  # Add Yarn node_modules folder to the asset load path.
+  # config.assets.paths << Rails.root.join('node_modules')
+
+  # Precompile additional assets.
+  # application.js, application.css, and all non-JS/CSS in the app/assets
+  # folder are already added.
+  # config.assets.precompile += %w( admin.js admin.css )
+end

config/initializers/content_security_policy.rb

@@ -0,0 +1,25 @@
+# Be sure to restart your server when you modify this file.
+
+# Define an application-wide content security policy
+# For further information see the following documentation
+# https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
+
+# Rails.application.config.content_security_policy do |policy|
+#   policy.default_src :self, :https
+#   policy.font_src    :self, :https, :data
+#   policy.img_src     :self, :https, :data
+#   policy.object_src  :none
+#   policy.script_src  :self, :https
+#   policy.style_src   :self, :https
+
+#   # Specify URI for violation reports
+#   # policy.report_uri "/csp-violation-report-endpoint"
+# end
+
+# If you are using UJS then enable automatic nonce generation
+# Rails.application.config.content_security_policy_nonce_generator = -> request { SecureRandom.base64(16) }
+
+# Report CSP violations to a specified URI
+# For further information see the following documentation:
+# https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy-Report-Only
+# Rails.application.config.content_security_policy_report_only = true

config/initializers/cookies_serializer.rb

@@ -1,3 +1,5 @@
 # Be sure to restart your server when you modify this file.
 
+# Specify a serializer for the signed and encrypted cookie jars.
+# Valid options are :json, :marshal, and :hybrid.
 Rails.application.config.action_dispatch.cookies_serializer = :json

config/initializers/docker.rb

@@ -1,6 +1,6 @@
 DockerClient.initialize_environment unless Rails.env.test? && `which docker`.blank?
 
-if ActiveRecord::Base.connection.tables.present? && DockerContainerPool.config[:active]
+if ApplicationRecord.connection.tables.present? && DockerContainerPool.config[:active]
   DockerContainerPool.start_refill_task
   at_exit { DockerContainerPool.clean_up }
 end

config/initializers/new_framework_defaults.rb

@@ -0,0 +1,20 @@
+# Be sure to restart your server when you modify this file.
+#
+# This file contains migration options to ease your Rails 5.0 upgrade.
+#
+# Once upgraded flip defaults one by one to migrate to the new default.
+#
+# Read the Guide for Upgrading Ruby on Rails for more info on each option.
+
+# Enable per-form CSRF tokens. Previous versions had false.
+Rails.application.config.action_controller.per_form_csrf_tokens = false
+
+# Enable origin-checking CSRF mitigation. Previous versions had false.
+Rails.application.config.action_controller.forgery_protection_origin_check = false
+
+# Make Ruby 2.4 preserve the timezone of the receiver when calling `to_time`.
+# Previous versions had false.
+ActiveSupport.to_time_preserves_timezone = false
+
+# Require `belongs_to` associations by default. Previous versions had false.
+Rails.application.config.active_record.belongs_to_required_by_default = false

config/initializers/new_framework_defaults_5_1.rb

@@ -0,0 +1,14 @@
+# Be sure to restart your server when you modify this file.
+#
+# This file contains migration options to ease your Rails 5.1 upgrade.
+#
+# Once upgraded flip defaults one by one to migrate to the new default.
+#
+# Read the Guide for Upgrading Ruby on Rails for more info on each option.
+
+# Make `form_with` generate non-remote forms.
+Rails.application.config.action_view.form_with_generates_remote_forms = false
+
+# Unknown asset fallback will return the path passed in when the given
+# asset is not present in the asset pipeline.
+# Rails.application.config.assets.unknown_asset_fallback = false

config/initializers/new_framework_defaults_5_2.rb

@@ -0,0 +1,38 @@
+# Be sure to restart your server when you modify this file.
+#
+# This file contains migration options to ease your Rails 5.2 upgrade.
+#
+# Once upgraded flip defaults one by one to migrate to the new default.
+#
+# Read the Guide for Upgrading Ruby on Rails for more info on each option.
+
+# Make Active Record use stable #cache_key alongside new #cache_version method.
+# This is needed for recyclable cache keys.
+# Rails.application.config.active_record.cache_versioning = true
+
+# Use AES-256-GCM authenticated encryption for encrypted cookies.
+# Also, embed cookie expiry in signed or encrypted cookies for increased security.
+#
+# This option is not backwards compatible with earlier Rails versions.
+# It's best enabled when your entire app is migrated and stable on 5.2.
+#
+# Existing cookies will be converted on read then written with the new scheme.
+# Rails.application.config.action_dispatch.use_authenticated_cookie_encryption = true
+
+# Use AES-256-GCM authenticated encryption as default cipher for encrypting messages
+# instead of AES-256-CBC, when use_authenticated_message_encryption is set to true.
+# Rails.application.config.active_support.use_authenticated_message_encryption = true
+
+# Add default protection from forgery to ActionController::Base instead of in
+# ApplicationController.
+# Rails.application.config.action_controller.default_protect_from_forgery = true
+
+# Store boolean values are in sqlite3 databases as 1 and 0 instead of 't' and
+# 'f' after migrating old data.
+# Rails.application.config.active_record.sqlite3.represent_boolean_as_integer = true
+
+# Use SHA-1 instead of MD5 to generate non-sensitive digests, such as the ETag header.
+# Rails.application.config.active_support.use_sha1_digests = true
+
+# Make `form_with` generate id attributes for any generated HTML tags.
+# Rails.application.config.action_view.form_with_generates_ids = true

config/initializers/wrap_parameters.rb

@@ -5,10 +5,10 @@
 
 # Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
 ActiveSupport.on_load(:action_controller) do
-  wrap_parameters format: [:json] if respond_to?(:wrap_parameters)
+  wrap_parameters format: [:json]
 end
 
 # To enable root element in JSON for ActiveRecord objects.
 # ActiveSupport.on_load(:active_record) do
-#  self.include_root_in_json = true
+#   self.include_root_in_json = true
 # end