Add test cases for the ContainerManager

cura/Settings/ContainerManager.py

@@ -47,8 +47,10 @@ class ContainerManager(QObject):
         if ContainerManager.__instance is not None:
             raise RuntimeError("Try to create singleton '%s' more than once" % self.__class__.__name__)
         ContainerManager.__instance = self
-
+        try:
             super().__init__(parent = application)
+        except TypeError:
+            super().__init__()
 
         self._application = application # type: CuraApplication
         self._plugin_registry = self._application.getPluginRegistry()  # type: PluginRegistry

tests/Settings/TestContainerManager.py

@@ -0,0 +1,32 @@
+from unittest import TestCase
+from unittest.mock import MagicMock
+
+from cura.Settings.ContainerManager import ContainerManager
+
+
+class TestContainerManager(TestCase):
+    def setUp(self):
+
+        self._application = MagicMock()
+        self._container_registry = MagicMock()
+        self._machine_manager = MagicMock()
+
+        self._containers_meta_data = [{"id": "test", "test_data": "omg"}]
+        self._container_registry.findContainersMetadata = MagicMock(return_value = self._containers_meta_data)
+
+        self._application.getContainerRegistry = MagicMock(return_value = self._container_registry)
+        self._application.getMachineManager = MagicMock(return_value = self._machine_manager)
+
+        # Destroy the previous instance of the container manager
+        if ContainerManager.getInstance() is not None:
+            ContainerManager._ContainerManager__instance = None
+
+        self._container_manager = ContainerManager(self._application)
+
+    def test_getContainerMetaDataEntry(self):
+        assert self._container_manager.getContainerMetaDataEntry("test", "test_data") == "omg"
+        assert self._container_manager.getContainerMetaDataEntry("test", "entry_that_is_not_defined") == ""
+
+    def test_clearUserContainer(self):
+        self._container_manager.clearUserContainers()
+        assert self._machine_manager.activeMachine.userChanges.clear.call_count == 1