class RuboCop::Cop::Rails::UniqueValidationWithoutIndex

def column_names_from_scope(uniqueness_part)
  return unless uniqueness_part.hash_type?
  scope = find_scope(uniqueness_part)
  return unless scope
  scope = unfreeze_scope(scope)
  case scope.type
  when :sym, :str
    [scope.value]
  when :array
    array_node_to_array(scope)
  end
end