Merge pull request #40025 from KapilSachdev/fix/uninitialized_instance_variable

fix: warning: instance variable @controller not initialized
Co-authored-by: NSamuel Williams <samuel.williams@oriontransfer.co.nz>

actionpack/lib/action_dispatch/testing/assertions/routing.rb

@@ -199,7 +199,8 @@ def recognized_request_for(path, extras = {}, msg)
             method = :get
           end
 
-          request = ActionController::TestRequest.create @controller.class
+          controller = @controller if defined?(@controller)
+          request = ActionController::TestRequest.create controller&.class
 
           if %r{://}.match?(path)
             fail_on(URI::InvalidURIError, msg) do