def METHOD_NAME(
    self, mock_get_policies, mock_get_models, mock_delete_store_signing_key
):
    mock_delete_store_signing_key.side_effect = StoreApiResponseErrorList(
        "Signing key is in use",
        409,
        [{"message": "key used to sign at least one serial policy"}],
    )
    mock_get_models.return_value = [{"name": "Model1"}]
    mock_get_policies.return_value = [
        {"revision": "1", "signing-key-sha3-384": "valid_key"}
    ]
    response = self.client.delete("/admin/store/1/signing-keys/valid_key")
    data = response.json
    self.assertEqual(response.status_code, 500)
    self.assertEqual(
        data["message"],
        "Signing key is used in at least one policy",
    )
    self.assertEqual(
        data["data"]["models"],
        [{"name": "Model1", "policies": [{"revision": "1"}]}],
    )