https://github.com/theforeman/foreman/commit/5da15d1ad20a71b65ad858d392e17fb46f074480 introduced a new issue of loading NIC models. Running specific tests fails because when loading Nic::Managed we loads Nic::Base which defined Nic::TYPES listing Nic::Managed (not loaded yet but in being loaded files array). Types are used only in API for listing values that can be used and it's converted to array of strings so we can safely define them as strings in class definition.