added test breaks for unavailable dns

develpoment environment is behind firewall rules that prohibit dns
access to public servers. -short flag skips tests that require external
dns resolver.

Author: wranders

.vscode/tasks.json

@@ -4,7 +4,7 @@
         {
             "label": "Go Coverage",
             "type": "shell",
-            "command": "go test -coverprofile='coverage.out'",
+            "command": "go test -short -coverprofile='coverage.out'",
             "options": {
                 "env": {
                     "CGO_ENABLED": "0"

action_test.go

@@ -157,6 +157,9 @@ func TestActionWildcardDNSMasq(t *testing.T) {
 }
 
 func TestListResolver(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping listresolver test; dns firewalling will cause this to fail")
+	}
 	http.DefaultTransport = nil
 	corefile := `filter {
 		listresolver 9.9.9.9
@@ -170,6 +173,9 @@ func TestListResolver(t *testing.T) {
 }
 
 func TestListResolverTLS(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping listresolver test; dns firewalling will cause this to fail")
+	}
 	http.DefaultTransport = nil
 	corefile := `filter {
 		listresolver tls://9.9.9.9 dns.quad9.net