infinite loop prevention: property path hints

Author: igneus

features/interactive.feature

@@ -221,5 +221,5 @@ Feature: It is possible to interactively fill in a form from the CLI
     And the output should contain
       """
         [RuntimeException]
-        Errors out of the form's scope - do you have validation constraints on properties not used in the form?
+        Errors out of the form's scope - do you have validation constraints on properties not used in the form? (Violations on unused fields: data.fieldNotUsedInTheForm)
       """

src/Console/Helper/FormHelper.php

@@ -7,8 +7,10 @@
 use Symfony\Component\Console\Helper\Helper;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Form\FormError;
 use Symfony\Component\Form\FormErrorIterator;
 use Symfony\Component\Form\FormInterface;
+use Symfony\Component\Validator\ConstraintViolationInterface;
 
 class FormHelper extends Helper
 {
@@ -73,7 +75,12 @@ public function interactUsingForm(
                 $formErrors = $form->getErrors(true, false);
                 $output->write(sprintf('Invalid data provided: %s', $formErrors));
                 if ($this->noErrorsCanBeFixed($formErrors)) {
-                    throw new \RuntimeException('Errors out of the form\'s scope - do you have validation constraints on properties not used in the form?');
+                    $violationPaths = $this->constraintViolationPaths($formErrors);
+                    $hint = (count($violationPaths) > 0 ? ' (Violations on unused fields: '.implode(', ', $violationPaths).')' : '');
+                    throw new \RuntimeException(
+                        'Errors out of the form\'s scope - do you have validation constraints on properties not used in the form?'
+                        . $hint
+                    );
                 }
                 array_map(
                     function (FormInterface $formField) use (&$validFormFields) {
@@ -101,4 +108,20 @@ protected function noErrorsCanBeFixed(FormErrorIterator $errors)
                 return $error instanceof FormErrorIterator;
             }));
     }
+
+    protected function constraintViolationPaths(FormErrorIterator $errors)
+    {
+        $paths = [];
+        foreach ($errors as $error) {
+            if (!$error instanceof FormError) {
+                continue;
+            }
+            $cause = $error->getCause();
+            if (!$cause instanceof ConstraintViolationInterface) {
+                continue;
+            }
+            $paths[] = $cause->getPropertyPath();
+        }
+        return $paths;
+    }
 }