Screen scraping is fragile. Mechanized web operation per se is not.

If the module you were installing was meant to do something specifically with Google, it would make sense to test against Google. Then a failure means the module does not work. If it tests a lower-level protocol (e.g. HTTP), it should use a peer to that protocol. But in the general case, Google is *not* a peer to screen scraping, since it never agreed to present web search results in a particular format.

It would be best if the tests of WWW::Mechanize targeted something with a stable protocol, for example if the module authors set up a test server. Or even a meta-server: people could volunteer test servers of their own, and the main server would just hand out a list of such servers for the client to choose from (through, for example, submitting a form :-)