Patch CuraApplication away while running tests for output devices

It needs CuraApplication because it wants to set metadata on the printer. But this is not relevant for the tests.

Contributes to issue CURA-8609.

tests/PrinterOutput/TestNetworkedPrinterOutputDevice.py

@@ -1,3 +1,6 @@
+# Copyright (c) 2021 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+
 import time
 from unittest.mock import MagicMock, patch
 
@@ -122,8 +125,9 @@ def test_put():
 
 def test_timeout():
     with patch("UM.Qt.QtApplication.QtApplication.getInstance"):
-        output_device = NetworkedPrinterOutputDevice(device_id="test", address="127.0.0.1", properties={})
-    output_device.setConnectionState(ConnectionState.Connected)
+        output_device = NetworkedPrinterOutputDevice(device_id = "test", address = "127.0.0.1", properties = {})
+    with patch("cura.CuraApplication.CuraApplication.getInstance"):
+        output_device.setConnectionState(ConnectionState.Connected)
 
     assert output_device.connectionState == ConnectionState.Connected
     output_device._update()
@@ -131,9 +135,8 @@ def test_timeout():
     output_device._last_response_time = time.time() - 15
     # But we did recently ask for a response!
     output_device._last_request_time = time.time() - 5
-    output_device._update()
+    with patch("cura.CuraApplication.CuraApplication.getInstance"):
+        output_device._update()
 
     # The connection should now be closed, since it went into timeout.
     assert output_device.connectionState == ConnectionState.Closed
-
-

tests/PrinterOutput/TestPrinterOutputDevice.py

@@ -1,7 +1,8 @@
-from unittest.mock import MagicMock
+# Copyright (c) 2021 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
 
 import pytest
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 
 from cura.PrinterOutput.Models.ExtruderConfigurationModel import ExtruderConfigurationModel
 from cura.PrinterOutput.Models.MaterialOutputModel import MaterialOutputModel
@@ -33,7 +34,8 @@ def test_getAndSet(data, printer_output_device):
     setattr(model, data["attribute"] + "Changed", MagicMock())
 
     # Attempt to set the value
-    getattr(model, "set" + attribute)(data["value"])
+    with patch("cura.CuraApplication.CuraApplication.getInstance"):
+        getattr(model, "set" + attribute)(data["value"])
 
     # Check if signal fired.
     signal = getattr(model, data["attribute"] + "Changed")