As example, we want to test your UA on test.com ? OK, easy. Start the baby server add this page. Make sure it is available via 127.0.0.1 . You use either a local proxy, or a virtual machine, or a locally connected second computer and edit hosts file on this second "device"
Hmm, and to test it on a "single" device, it's enough to edit its host file?
And/or to use KM-proxy pr