I think this test looks good.  One thing I can't immediately tell from this test alone, though, is that the CA cert is actually being used to validate the server as opposed to the server just being trusted automatically with no validation being done.  If we had a similar companion test which showed that if a CA cert which is incompatible with the server cert resulted in a failure on the get request, I think we'd have better confidence that the CA cert is really being used as expected in the success case.