Improve high order testing

IO/CGNS/Testing/Cxx/TestCGNSReaderHOElements.cxx

@@ -9,8 +9,12 @@
 #include "vtkMultiBlockDataSet.h"
 #include "vtkNew.h"
 #include "vtkPointData.h"
+#include "vtkCellData.h"
 #include "vtkTestUtilities.h"
 #include "vtkUnstructuredGrid.h"
+#include "vtkCellSizeFilter.h"
+
+#define compare_double(x, y, e) ((x) - (y) < (e) && (x) - (y) > -(e))
 
 int TestCGNSReaderHOElements(int argc, char* argv[])
 {
@@ -73,5 +77,30 @@ int TestCGNSReaderHOElements(int argc, char* argv[])
     return EXIT_FAILURE;
   }
 
+  // To check the point ordering, just compute the cell volume...
+  // It could also be possible to do an image comparison.
+  vtkNew<vtkCellSizeFilter> checkerSize;
+  checkerSize->SetInputData(internal_hexa_125);
+  checkerSize->ComputeVolumeOn();
+  checkerSize->Update();
+  auto res = vtkDataSet::SafeDownCast(checkerSize->GetOutputDataObject(0));
+  auto cdata = res->GetCellData();
+  auto volume = vtk::DataArrayValueRange<1>(cdata->GetArray("Volume"));
+
+  if (!compare_double(volume[0], 2000., 1.0e-6)) {
+    return EXIT_FAILURE;
+  }
+
+  checkerSize->SetInputData(internal_hexa_64);
+  checkerSize->ComputeVolumeOn();
+  checkerSize->Update();
+  auto res_2 = vtkDataSet::SafeDownCast(checkerSize->GetOutputDataObject(0));
+  auto cdata_2 = res_2->GetCellData();
+  auto volume_2 = vtk::DataArrayValueRange<1>(cdata_2->GetArray("Volume"));
+
+  if (!compare_double(volume_2[0], 216., 1.0e-6)) {
+    return EXIT_FAILURE;
+  }
+
   return EXIT_SUCCESS;
 }

IO/CGNS/vtk.module

@@ -26,3 +26,5 @@ TEST_DEPENDS
   VTK::InteractionStyle
   VTK::TestingCore
   VTK::TestingRendering
+  VTK::FiltersGeneral
+  VTK::FiltersVerdict