// determine that value and use it in the "expected" results for the test
// cases in TestResolveAddr(). Need to wrap IPv6 addresses in square
// brackets.
func determineLocalHostIPString(t *testing.T) string {
	ips, err := net.DefaultResolver.LookupNetIP(context.Background(), "ip", "localhost")
	if err != nil || len(ips) == 0 {
		t.Fatalf("Test setup failure - unable to determine IP of localhost: %v", err)