Question

Suppose you have a similar YAML configuration file:

defaults: &defaults
  # registration form
  birth_date: true
  address: true
  zip: true
  city: true
  state: true
  # other stuff
  send_email_notification_to_users: true

production:
  <<: *defaults

development:
  <<: *defaults

test:
  <<: *defaults

which is loaded in a similar way to how it is explained in Railcast #85:
http://railscasts.com/episodes/85-yaml-configuration-file

Suppose you need to test how the application performs with different settings, how would you do that?

With Django it is possible to change the settings temporarily during unit tests:
https://docs.djangoproject.com/en/dev/topics/testing/overview/#overriding-settings

Is it possible to do something similar with Rails?

Answer 1

In case you implemented it exactly like it is explained in Railscast #85, simply assign the new value like so:

APP_CONFIG['perform_authentication'] = false
# or
APP_CONFIG['my_fancy_key'] = 'my fancy value'

Keep in mind that the value will not be changed back automatically after your test case finished, so it will remain valid for all subsequent test cases.