'Storage.get_valid_name() should be called when upload_to is a callable.'

def test_custom_valid_name_callable_upload_to(self):

    obj = Storage()
    obj.custom_valid_name.save('random_file', ContentFile('random    content'))
    self.assertTrue(obj.custom_valid_name.name.endswith('/random_file_valid'))
    obj.custom_valid_name.close()
