def METHOD_NAME(self):
    """Assert that not modified response is handled correctly"""
    project = models.Project(
        name="whisker",
        homepage="https://github.com/edwindj/whisker",
        backend=BACKEND,
    )
    exp_url = "https://crandb.r-pkg.org/whisker/all"
    with mock.patch("anitya.lib.backends.BaseBackend.call_url") as m_call:
        m_call.return_value = mock.Mock(status_code=304)
        versions = backend.CranBackend.get_versions(project)
        m_call.assert_called_with(exp_url, last_change=None)
        self.assertEqual(versions, [])