test.rb

class RoutingErrorRaiser
  def initialize(app)
    @app = app
  end

  def call(env)
    status, headers, body = @app.call(env)
    raise ActionController::RoutingError, "No route matches #{env['PATH_INFO'].inspect}" if headers['X-Cascade'] == 'pass'
    [status, headers, body]
  end
end

Lettercase::Application.configure do
  config.middleware.use ::RoutingErrorRaiser