use offscreen rendering in VTK unit tests

.github/workflows/docker_build_test_publish.yml

@@ -33,5 +33,5 @@ jobs:
       - name: Run docker container with tests
         shell: bash -l {0}
         run: |
-          docker run --rm --entrypoint /bin/bash -v /home/runner/work/CILViewer/CILViewer:/root/source_code  cil-viewer -c "source ./mambaforge/etc/profile.d/conda.sh && conda activate cilviewer_webapp && conda install cil-data pytest pyside2 eqt>=1.0.0 -c ccpi && python -m pytest /root/source_code/Wrappers/Python -k 'not test_version and not test_cli_resample and not test_CILViewerBase and not test_CILViewer3D and not test_viewer_main_windows and not test_ui_dialogs'"
+          docker run --rm --entrypoint /bin/bash -v /home/runner/work/CILViewer/CILViewer:/root/source_code  cil-viewer -c "source ./mambaforge/etc/profile.d/conda.sh && conda activate cilviewer_webapp && conda install cil-data pytest pyside2 eqt>=1.0.0 -c ccpi && python -m pytest /root/source_code/Wrappers/Python -k 'not test_version and not test_cli_resample and not test_viewer_main_windows and not test_ui_dialogs'"
     # TODO: publish to come later

Wrappers/Python/test/test_CILViewer3D.py

@@ -20,11 +20,9 @@
 
 from ccpi.viewer.CILViewer import CILViewer
 
-# skip the tests on GitHub actions
-if os.environ.get('CONDA_BUILD', '0') == '1':
-    skip_test = True
-else:
-    skip_test = False
+from vtkmodules.vtkRenderingCore import vtkGraphicsFactory
+
+skip_test = False
 
 print("skip_test is set to ", skip_test)
 
@@ -33,6 +31,10 @@
 class CILViewer3DTest(unittest.TestCase):
 
     def setUp(self):
+        vgf = vtkGraphicsFactory()
+        vgf.SetOffScreenOnlyMode(True)
+        vgf.SetUseMesaClasses(True)
+        self.vgf = vgf
         self.cil_viewer = CILViewer()
 
     def test_getGradientOpacityPercentiles_returns_correct_percentiles_when_image_values_start_at_zero(self):

Wrappers/Python/test/test_CILViewerBase.py

@@ -19,12 +19,9 @@
 import os
 
 from ccpi.viewer.CILViewer import CILViewerBase
+from vtkmodules.vtkRenderingCore import vtkGraphicsFactory
 
-# skip the tests on GitHub actions
-if os.environ.get('CONDA_BUILD', '0') == '1':
-    skip_test = True
-else:
-    skip_test = False
+skip_test = False
 
 print("skip_test is set to ", skip_test)
 
@@ -34,6 +31,10 @@ class CILViewerBaseTest(unittest.TestCase):
 
     def setUp(self):
         '''Creates an instance of the CIL viewer base class.'''
+        vgf = vtkGraphicsFactory()
+        vgf.SetOffScreenOnlyMode(True)
+        vgf.SetUseMesaClasses(True)
+        self.vgf = vgf
         self.CILViewerBase_instance = CILViewerBase()
 
     def test_setAxisLabels(self):
@@ -56,6 +57,7 @@ def test_setAxisLabels(self):
 class CILViewer3DTest(unittest.TestCase):
 
     def setUp(self):
+        vgf = vtkGraphicsFactory(off_screen_only_mode=True, use_mesa_classes=True)
         self.cil_viewer = CILViewerBase()
 
     def test_getSliceColorPercentiles_returns_correct_percentiles_when_slice_values_start_at_zero(self):