I cannot add default value for file type in form builder. Theoretically it should work, when I use name of not-existing file, it throws an exception. However each time when I pass the form, I have to choose a file to upload.
My form builder:
public function buildForm(FormBuilderInterface $builder, array $options) {
$builder
->add('photo', 'file', array('label' => 'user.userinfo.properties.photo', 'data' => $builder->getData()->getPhotoAsFile()))
;
}