Thanks Andras, I asked there (they confirmed it is a limitation currently), and implemented the workaround you suggested. Currently I am doing this in a copy of itkTestMain.h in my project/slicer module. When I put the pull request up for that project, I could share it here, if you’d like to see if it is worth considering integrating it into Slicer!?
If the file is not part of Slicer then please send us a pull request and we’ll merge your improvements. It would be great if you could also add a test somewhere that uses the new vector image compare feature (e.g., you could add a new test to one of the CLI modules).