Some small changes for the URL test (#1910)
Some small changes for the URL test (#1910)

I was looking at the #923 (it'll be quite some effort to get the
informer there, or create dynamic one for k8s services),
but nonetheless clean the test up.

- Rename the getters to exclude word get (as go style suggests).
- The errors test contains only errors, so stream line it
- Ensure errors are also idempotent, which wasn't.
knative/pkg,knative/pkg