refactor: move a func that is only used in testing

nameserver/mdns_client.go

@@ -105,11 +105,6 @@ func LinkLocalMulticastListener(ifi *net.Interface) (net.PacketConn, error) {
 
 type MDNSAction func()
 
-// Async
-func (c *MDNSClient) Shutdown() {
-	c.actionChan <- nil
-}
-
 // Async
 func (c *MDNSClient) SendQuery(name string, querytype uint16, responseCh chan<- *Response) {
 	c.actionChan <- func() {

nameserver/mdns_client_test.go

@@ -85,6 +85,10 @@ func setup(t *testing.T) (*MDNSClient, *dns.Server, error) {
 	return mdnsClient, server, err
 }
 
+func (c *MDNSClient) Shutdown() {
+	c.actionChan <- nil
+}
+
 type testContext struct {
 	receivedAddr  net.IP
 	receivedCount int