module GraphQL::StaticValidation::DirectivesAreDefined

def initialize(*)
  super
  @directive_names = context.warden.directives.map(&:graphql_name)
end

def on_directive(node, parent)
  if !@directive_names.include?(node.name)
    @directives_are_defined_errors_by_name ||= {}
    error = @directives_are_defined_errors_by_name[node.name] ||= begin
      err = GraphQL::StaticValidation::DirectivesAreDefinedError.new(
        "Directive @#{node.name} is not defined",
        nodes: [],
        directive: node.name
      )
      add_error(err)
      err
    end
    error.nodes << node
  else
    super
  end
end