Toggle features in development mode by touching various tmp/*.txt files.

development.rb

# Touch tmp/caching.txt to turn on caching
if Rails.root.join('tmp/caching.txt').exist?
  config.action_controller.perform_caching = true
  config.cache_store = :mem_cache_store
else
  config.action_controller.perform_caching = false
  config.cache_store = :null_store
end
 
# Touch tmp/precompile.txt to test with asset precompiles. Run
#   RAILS_ENV=development RAILS_GROUPS=assets rake assets:precompile
# to compile the assets, then `touch tmp/restart.txt`
if Rails.root.join('tmp/precompile.txt').exist?
  config.assets.compile   = false
  config.assets.digest    = true
  config.assets.compress  = false
end
 
# Touch tmp/mocksmtp.txt to deliver mail to MockSMTP.app
if Rails.root.join('tmp/mocksmtp.txt').exist?
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = { address: 'localhost', port: 1025, domain: 'example.com' }
else
  config.action_mailer.raise_delivery_errors = false
end