We should create a network wrapper object (like we have for the filesystem now) add pass that to objects that need to fetch things over the net, like the json_results* classes (and rebaseline-chromium-webkit-tests). That'll speed up unit testing and make it more reliable, as well as allow us to get better coverage of the code.
I agree. Bugzilla needs this for better mocking as well. Currently we have BugzillaQueries which allows similar mocking at a slightly higher level.
see bug 53040, which adds the first attempt at a network wrapper.
I've added the wrapper in common/system/urlfetcher.py, and we have a separate bug for tracking the json work, so I'm closing this now.