module Devise::Test::ControllerHelpers

def sign_in(resource, deprecated = nil, scope: nil)

sign_in users(:alice), scope: :admin
sign_in users(:alice)

Examples:
should be signed in with.
* +scope+ - An optional +Symbol+ with the scope where the resource
* +resource+ - The resource that should be authenticated

This method bypass any warden authentication callback.
sign_in a given resource by storing its keys in the session. 
def sign_in(resource, deprecated = nil, scope: nil)
  if deprecated.present?
    scope = resource
    resource = deprecated
    ActiveSupport::Deprecation.warn <<-DEPRECATION.strip_heredoc
      [Devise] sign_in(:#{scope}, resource) on controller tests is deprecated and will be removed from Devise.
      Please use sign_in(resource, scope: :#{scope}) instead.
    DEPRECATION
  end
  scope ||= Devise::Mapping.find_scope!(resource)
  warden.instance_variable_get(:@users).delete(scope)
  warden.session_serializer.store(resource, scope)
end