def METHOD_NAME(self):
    """Assert that not modified response is handled correctly"""
    pid = 1
    project = models.Project.get(self.session, pid)
    exp_url = "https://crates.io/api/v1/crates/itoa/versions"
    with mock.patch("anitya.lib.backends.BaseBackend.call_url") as m_call:
        m_call.return_value = mock.Mock(status_code=304)
        versions = crates.CratesBackend.get_versions(project)
        m_call.assert_called_with(exp_url, last_change=None)
        self.assertEqual(versions, [])