'get_storage_class raises an error if the requested class don\'t exist.'

def test_get_nonexisting_storage_class(self):

    self.assertRaisesMessage(ImproperlyConfigured, u'Module    "django.core.files.storage"    does    not    define    a    "NonExistingStorage"    attribute/class', get_storage_class, u'django.core.files.storage.NonExistingStorage')
