Since I think running clustering tests and checking for openshift specific behavior are somewhat orthogonal (at least at the moment). A good first step might be to use microshift. I don't know if it would be a drop in vs minikube or k3d but I think that it may be worth a try.
Microshift has promising potential: I managed to deploy the samba-operator and AD over microshift (within fedora VM), but still, so far I failed to run the tests-suite successfully. More investigation is needed.
Since I think running clustering tests and checking for openshift specific behavior are somewhat orthogonal (at least at the moment). A good first step might be to use microshift. I don't know if it would be a drop in vs minikube or k3d but I think that it may be worth a try.