Defensive Testing

It seems that homeschoolers are often homeschooling because they don't like that schools seem to "teach to the test" or think that tests are not a good measurement of how well a child is educated.  What about testing as a defensive measure?  In New York State, standardized tests must be given every other year starting in 4th grade, but not all states require them.  When T finished kindergarten before he turned 5 I thought that there would be many people, maybe at the school district, but more likely naysaying extended family members or acquaintances who would question whether he really learned what he was supposed to learn by that age without going to school.  I decided to take a chance on it and give him the California Achievement Test for kindergarten thinking that, by the standards of those who believe in conventional school, it would prove that he really did well enough in kindergarten to proceed.  Fortunately, he scored 60 percentile or above on everything.  While I don't believe that standardized tests are a great measure of acheivement, it feels like one more piece of evidence that we are on the right track.  What do you think about defensive standarized testing?