Symfony\Component\Form\Extension\Validator\Constraints\FormValidator::validate PHP Method

    public function validate($form, Constraint $constraint)
    {
        if (!$constraint instanceof Form) {
            throw new UnexpectedTypeException($constraint, __NAMESPACE__.'\Form');
        }

        if (!$form instanceof FormInterface) {
            return;
        }

        /* @var FormInterface $form */
        $config = $form->getConfig();

        $validator = $this->context->getValidator()->inContext($this->context);

        if ($form->isSynchronized()) {
            // Validate the form data only if transformation succeeded
            $groups = self::getValidationGroups($form);
            $data = $form->getData();

            // Validate the data against its own constraints
            if ($form->isRoot() && (is_object($data) || is_array($data))) {
                if (is_array($groups) && count($groups) > 0 || $groups instanceof GroupSequence && count($groups->groups) > 0) {
                    $validator->atPath('data')->validate($form->getData(), null, $groups);
                }
            }

            // Validate the data against the constraints defined
            // in the form
            $constraints = $config->getOption('constraints', array());
            foreach ($constraints as $constraint) {
                // For the "Valid" constraint, validate the data in all groups
                if ($constraint instanceof Valid) {
                    $validator->atPath('data')->validate($form->getData(), $constraint, $groups);

                    continue;
                }

                // Otherwise validate a constraint only once for the first
                // matching group
                foreach ($groups as $group) {
                    if (in_array($group, $constraint->groups)) {
                        $validator->atPath('data')->validate($form->getData(), $constraint, $group);

                        // Prevent duplicate validation
                        continue 2;
                    }
                }
            }
        } else {
            $childrenSynchronized = true;

            foreach ($form as $child) {
                if (!$child->isSynchronized()) {
                    $childrenSynchronized = false;
                    break;
                }
            }

            // Mark the form with an error if it is not synchronized BUT all
            // of its children are synchronized. If any child is not
            // synchronized, an error is displayed there already and showing
            // a second error in its parent form is pointless, or worse, may
            // lead to duplicate errors if error bubbling is enabled on the
            // child.
            // See also https://github.com/symfony/symfony/issues/4359
            if ($childrenSynchronized) {
                $clientDataAsString = is_scalar($form->getViewData())
                    ? (string) $form->getViewData()
                    : gettype($form->getViewData());

                $this->context->buildViolation($config->getOption('invalid_message'))
                    ->setParameters(array_replace(array('{{ value }}' => $clientDataAsString), $config->getOption('invalid_message_parameters')))
                    ->setInvalidValue($form->getViewData())
                    ->setCode(Form::NOT_SYNCHRONIZED_ERROR)
                    ->setCause($form->getTransformationFailure())
                    ->addViolation();
            }
        }

        // Mark the form with an error if it contains extra fields
        if (!$config->getOption('allow_extra_fields') && count($form->getExtraData()) > 0) {
            $this->context->buildViolation($config->getOption('extra_fields_message'))
                ->setParameter('{{ extra_fields }}', implode('", "', array_keys($form->getExtraData())))
                ->setInvalidValue($form->getExtraData())
                ->setCode(Form::NO_SUCH_FIELD_ERROR)
                ->addViolation();
        }
    }

 public function testNoViolationIfNotRoot()
 {
     $this->serverParams->expects($this->once())->method('getContentLength')->will($this->returnValue(1025));
     $this->serverParams->expects($this->never())->method('getNormalizedIniPostMaxSize');
     $context = $this->getExecutionContext();
     $parent = $this->getBuilder()->setCompound(true)->setDataMapper($this->getDataMapper())->getForm();
     $form = $this->getForm();
     $parent->add($form);
     $this->validator->initialize($context);
     $this->validator->validate($form, new Form());
     $this->assertCount(0, $context->getViolations());
 }