Service stubbing in Rails

service_stubbing_in_rails.md

Example: stubbing a service object in a Rails application

app/models/services/sharepoint.rb (partial):

module SharePoint

  # Live SharePoint Context class, uses OAuth2 and RestClient
  # to talk to the outside world
  class LiveContext

    # Returns current authenticated SharePoint::User
    def current_user
      User.from_xml(
        self,
        rest_api['SP.UserProfiles.PeopleManager/GetMyProperties?$select=AccountName'].get
      )
    end

  end

  # Stub SharePoint Context class, provides canned responses
  # without calling remote web services 
  class StubContext < LiveContext

    def current_user
      User.new(self, 'stub account name')
    end

  end

  # Choose Context implementation based on application config, if any.
  # Default is Live.
  # Available to the app as SharePoint::Context
  Context = (
    APP_CONFIG[:test_doubles][:sharepoint_context] || 'SharePoint::LiveContext'
  ).constantize

end

config/app_config.yml (partial):

# Application configuration settings
defaults: &defaults
  test_doubles: {}

development:
  <<: *defaults

test:
  <<: *defaults
  test_doubles:
    sharepoint_context: SharePoint::StubContext

production:
  <<: *defaults