Fix #557 - mac addess collision when running IOU on multiple GNS3 servers

tests/compute/iou/utils/test_application_id.py

@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2017 GNS3 Technologies Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import pytest
+from unittest.mock import MagicMock
+from gns3server.compute.iou.utils.application_id import get_next_application_id, IOUError
+
+
+def test_get_next_application_id():
+    # test first node
+    assert get_next_application_id([]) == 1
+
+    # test second node
+    nodes = [
+        MagicMock(node_type='different'),
+        MagicMock(node_type='iou', properties=dict(application_id=1))
+    ]
+    assert get_next_application_id(nodes) == 2
+
+    # test reach out the limit
+    nodes = [MagicMock(node_type='iou', properties=dict(application_id=i)) for i in range(1, 512)]
+
+    with pytest.raises(IOUError):
+        get_next_application_id(nodes)