Refactoring: DNS App (#169)

Co-authored-by: loyalsoldier <10487845+Loyalsoldier@users.noreply.github.com>

app/dns/nameserver_local_test.go

@@ -0,0 +1,25 @@
+package dns_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	. "v2ray.com/core/app/dns"
+	"v2ray.com/core/common"
+	"v2ray.com/core/common/net"
+)
+
+func TestLocalNameServer(t *testing.T) {
+	s := NewLocalNameServer()
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*2)
+	ips, err := s.QueryIP(ctx, "google.com", net.IP{}, IPOption{
+		IPv4Enable: true,
+		IPv6Enable: true,
+	})
+	cancel()
+	common.Must(err)
+	if len(ips) == 0 {
+		t.Error("expect some ips, but got 0")
+	}
+}