So now I understand why you care about the version of zypper, I understand what these classes should be called.

Please do not refer to SLES versions when what you are checking is zypper versions. This is just confusing, and will not grow old well... Can you imagine having to use the "zypper_version_newer_than_sles10" when using SLES 12? How confusing would that be!?

So, unless you have an objection, please call them "zypper_version_ok" and "zypper_version_unusable".