Add test for global stack getting user changes

Tests fail right now because running the test actually deletes files. Got to fix that.

Contributes to issue CURA-3497.

tests/Settings/TestGlobalStack.py

@@ -0,0 +1,33 @@
+# Copyright (c) 2017 Ultimaker B.V.
+# Cura is released under the terms of the AGPLv3 or higher.
+
+import os.path #To find the test files.
+import pytest #This module contains unit tests.
+import unittest.mock #To monkeypatch some mocks in place of dependencies.
+
+from cura.Settings.GlobalStack import GlobalStack #The module we're testing.
+from UM.Settings.DefinitionContainer import DefinitionContainer #To test against the class DefinitionContainer.
+import UM.Settings.ContainerRegistry
+
+##  Tests whether the user changes are being read properly from a global stack.
+@pytest.mark.parametrize("filename, user_changes_id", [
+                        ("Global.global.cfg", "empty"),
+                        ("Global.stack.cfg", "empty"),
+                        ("MachineLegacy.stack.cfg", "empty")
+])
+def test_deserializeUserChanges(filename, user_changes_id):
+    with open(os.path.join(os.path.dirname(os.path.abspath(__file__)), "stacks", filename)) as file_handle:
+        serialized = file_handle.read()
+    stack = GlobalStack("TestStack")
+
+    #Mock the loading of the instances.
+    def findContainer(container_id = "*", container_type = None, type = None, category = "*"):
+        if id == "some_material":
+            return UM.Settings.ContainerRegistry._EmptyInstanceContainer(id)
+        if container_type == DefinitionContainer:
+            return unittest.mock.MagicMock()
+    stack.findContainer = findContainer
+
+    stack.deserialize(serialized)
+
+    assert stack.userChanges.getId() == user_changes_id