'Ensure fields with document choices validate given a valid choice.'

def test_choices_validation_documents(self):

    class UserComments(EmbeddedDocument, ):
        author = StringField()
        message = StringField()
    class BlogPost(Document, ):
        comments = ListField(GenericEmbeddedDocumentField(choices=(UserComments,)))
    BlogPost(comments=[UserComments(author='user2', message='message2')]).save()
