nothing says the test airing will not include nationwide airings.
these tests are to see the best response in terms of costs.
so if it costs $200,000 for one spot on a national channel with 4m viewers will I get more sales than $200,000 spent on 10 spots a regional channel with 1m viewers.
you need to do a number of well thought out combinations to work out your best ROI, monitoring clicks on web site as well as phone calls, plus for every sale you need to ask where they saw the commercial etc.
So national exposure is almost certainly part of the test airing - it just wont be seen alongside every GEICO commercial.
Just a thought - could they run during the superbowl pre/postgame shows?